Multiphoton up-conversion emission from diamond single crystals

High-quality single-crystal diamond, which has an energy bandgap of 5.5 eV, ... demonstrated by using a tunable femtosecond laser as the excitation so...
0 downloads 3 Views 1MB Size
Subscriber access provided by Kaohsiung Medical University

Functional Inorganic Materials and Devices

Multiphoton up-conversion emission from diamond single crystals Yunfeng Wang, Wenfei Zhang, Chao-Nan Lin, Pengpeng Ren, Ying-Jie Lu, Chongxin Shan, and Siu Fung Yu ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b07288 • Publication Date (Web): 17 May 2018 Downloaded from http://pubs.acs.org on May 17, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

Multiphoton up-conversion emission from diamond single crystals Yunfeng Wang1,+, Wenfei Zhang2,+*, Chao-Nan Lin3, Pengpeng Ren2, Ying-Jie Lu3, Chongxin Shan3,*, Siu Fung Yu1,* 1 2

3

Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong, China Shenzhen Key Laboratory of Laser Engineering, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China School of Physics and Engineering, Zhengzhou University, Zhengzhou 450052, China

Abstract – Room-temperature up-conversion emission up to eight-photon absorption is demonstrated from diamond single crystals under femtosecond laser excitation for the first time. The low concentration of defects and impurities is attributed to the support of free excitons emission at 235 nm. Nonlinear optical properties are also investigated by using an open-aperture Z-scan technique. The corresponding three-, five- and eight-photon absorption coefficients of the diamonds are found to be 1.8×10–2 cm3/GW2, 5×10–9 cm7/GW4 and 1.6×10–19 cm13/GW7 respectively. Considering its high hardness and high thermal conductivity, diamonds are a versatile nonlinear optical material suitable for high-power deep ultraviolet applications under multi-photon excitation. Keywords – diamond single crystals, upconversion emission, nonlinear optical absorption, photoluminescence, nonlinear optics.

+ authors with equal contribution * corresponding authors [email protected]

email:

[email protected],

1 ACS Paragon Plus Environment

[email protected],

ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

1. Introduction High-quality single-crystal diamond, which has an energy bandgap of 5.5 eV, is expected to support high-temperature free excitons (FEs) emission at ~235 nm due to its high excitonic binding energy (i.e. 80.5 meV). In fact, FEs emission has been observed from diamond films and single crystals at low temperature.1-5 For a diamond with an impurity-defect density lower than 1018 cm-3, high-intensity FEs radiative recombination can be realized at room temperature.2-3 In contrast, the presence of defects and impurities increases the nonradiative recombination centers of FEs. Lipatov studied the cathodoluminescence (CL) spectra of two different polycrystalline chemical vapor deposition diamonds and found that the weak FEs emission is attributed to the “non-diamond” bands including amorphous carbon, disoriented graphite, and microcrystalline area.2 Yokota3 also compared the emission intensities of FEs band and band-A (350-650 nm luminescence originates from dislocations6-7 and imperfect lattice8-9 of diamond films), they revealed that the increase in boron impurity induced “nondiamond” bands. As a result, FEs emission was suppressed in the CL spectra. Furthermore, Liaugaudas assessed the influence of defects on the FEs peak (at 235 nm) of diamonds at 80 K. The intensity of FEs emission increases by approximately five-fold after the sample undergoes thermal annealing at 1200 oC to remove defects.4 Diamond also demonstrates multiphoton absorption under high-power laser excitation. Twoand three-photon absorptions in mono- and nano-crystalline diamond had been studied.5, 10-13 However, to the best of our knowledge, there is no report on the investigation of multiphoton emission from the single-crystal diamonds. This may be due to the difficulty to realize diamonds with a low concentration of defect states. Here, we report the possibility to fabricate high-quality single-crystal diamond by using microwave plasma chemical vapor deposition (MPCVD) method to support strong FEs emission at room temperature. It is found that the growth of (100) orientation diamond single crystal strongly suppresses defects and promotes FEs radiative recombination. FEs emission from the diamond under multiphoton excitation is also demonstrated by using a tunable femtosecond laser as the excitation source. Room-temperature photoluminescence (PL) intensity with an emission peak at a wavelength of ~235 nm (i.e. ~5.28 eV) is observed under laser excitation with wavelength varies from 800 to 1900 nm (i.e. 1.55 – 0.65 eV). Furthermore, it is verified that the supreme optical and mechanical properties of single crystal diamonds support room-temperature FEs emission under eight-photon excitation. Therefore, single crystal diamond is a nonlinear optical material suitable for high-power deep ultraviolet applications under multi-photon excitation. 2 ACS Paragon Plus Environment

Page 2 of 15

Page 3 of 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

2. Results and Discussion Fig. 1a shows the diamond PDF reference and the measured x-ray diffraction (XRD) patterns of the single crystal diamonds (i.e. bulk-1 to bulk-4, see experimental section). It is noted that the (022) and (113) planes are not detected from the diamonds. The (022) and (113) planes, which are very rarely for the synthesized diamond crystals due to their fast growth rate, are not the ideal orientation to grow large-area epitaxial films or crystals. Moreover, these faces are prone to micro-faceting which will lead to surface roughness.14 On the other hand, many investigations have reported that (111) faces presenting some disadvantages for the growth of chemical vapor deposition diamond – the surface atomic configuration can induce defects and incorporate impurities during the growth process.15-20 Hence, the presence of strong (111) peak indicates that the diamonds have the high defect and impurity states. In fact, it is expected that the high-optical-quality single crystal diamonds should have a dominant (100) peak.

Fig.1. (a) XRD patterns, (b) UV-vis absorption spectra, (c) FTIR patterns and (d) Room-temperature downconversion PL spectra of the diamond samples excited by 215 nm nanosecond laser beam at a pump power of 0.002 GW/cm2 for the four (i.e. bulk-1, bulk-2, bulk-3 and bulk-4) diamond single crystals. The insets of (b) show the optical photograph of the samples.

3 ACS Paragon Plus Environment

ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Fig. 1a shows that the four samples have (111) and (400) peaks. This indicates that the crystalline orientations of the samples are originated from the and directions. The intensity ratio between the (400) and (111) peaks, I(400)/I(111), is measured. I(400)/I(111) for bulk-1, bulk-2, bulk-3, and bulk-4 are found to be 15.0, 4.58, 0.91 and 0.33 respectively. Hence, the bulk-1 exhibits a high-quality -oriented single crystal structure but the -oriented single crystal structure dominates the bulk-4. All the diamonds consist of highly uniform C-C bonds in a tetrahedral crystal structure, which can be identified by Raman spectra (Fig. S1). A single Raman band at 1332 cm–1 is due to the F2g mode of the diamonds. Some broad bands (1350-1600 cm-1) which are characteristics of amorphous carbon and their sp2 structures can be found in bulk-2, bulk-3, and bulk-4. Fig.1b shows UVvisible absorption spectra of the bulk samples. A peak at 270 nm arises from substitutional nitrogen in bulk-1 is lowed that from the other samples. Bulk-4 exhibits strong absorption in the region from 200 to 550 nm due to the high nitrogen concentration. In the Fourier transform infrared (FTIR) spectra shown in Fig. 1c, the region from 2680 to 1600 cm-1 refers to the intrinsic multi-phonon absorption from the C-C bond of the diamond.21-22 The typical diamond peak at 2160 cm-1 is seen for all the samples. On the other hand, it is noted that peaks emerge from the spectral regime between 1400 and 1050 cm-1 represents the presence of nitrogen defects such as N2 (A centers), N4 (B centers), single substitutional nitrogen defects (C centers) and platelets.23 Hence, single substitutional nitrogen defects locate at 1130 and 1344 cm-1 of the FTIR spectrum have revealed that bulk-4 contains high nitrogen concentration of about 265 ppm (supporting information, section B), 24-25 which is consistent with the result shown in UV-vis spectra. However, bulk-1, bulk-2, and bulk-3 do not show an obvious peak at the position of nitrogen defects. XPS data shows that the bulk-4 has the highest nitrogen content (Table S1). Fig. 1d plots the down-conversion photoluminescence (PL) spectra of the samples under 215 nm nanosecond pulsed excitation at 298 K. The bulk-1 PL peaks (at 235 and 242 nm), which are assigned to the FEs recombination band, are stronger than that of the other samples. Therefore, we confirm that the diamonds with strong -oriented single crystal structure, the influence of defects and impurities states can be suppressed. As a result, high FEs emission intensity is supported by optical excitation at 298 K and the high-optical-quality of bulk-1 is suitable for multiphoton emission applications. The influence of defects and impurities on the PL spectra of the diamonds was studied by using 325 and 488 nm continuous wave lasers (Fig. S2). It is noted that FEs radiative recombination band in the defective diamonds is suppressed by the band-A emission. Bulk-2, 4 ACS Paragon Plus Environment

Page 4 of 15

Page 5 of 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

bulk-3, and bulk-4 show strong band-A emission from 500 to 700 nm, which can be attributed to the optical transitions in the N4V center, dislocations, grain boundaries or other defects.2, 7, 26-29 Under 325 nm excitation at 298 K, the visible PL intensity of bulk-3 is higher than that of bulk-1 and bulk-2, which indicates more defects are contained in bulk-3 (Fig. S2a). A similar phenomenon was also observed under 488 nm excitation at 298 K, and weak zero-phonon lines (ZPL) emission at 575 and 637 nm, which originated from the nitrogenvacancy NV0 and NV- centers,30-31 are observed in bulk-1, bulk-2 and bulk-3 (Fig. S2b). Furthermore, the PL spectra of bulk-1, bulk-2, and bulk-3 were measured at 77 K under 488 nm excitation (Fig. S2c). After normalized to T2g Raman peak of diamond at 522 nm, the intensity of the peak at 575 and 637 nm in bulk-3 (bulk-2) is found to be 5-6 (1-2) folds higher than that of the bulk-1 (Fig. S2d). This means that bulk-2 and -3 have more defects caused by nitrogen-vacancy than that of bulk-1. Hence, it is verified that emission due to defects and impurities is strongly suppressed in the bulk-1 and this result is consistent with the analysis given in Fig. 1.

Fig. 2. (a) Up-conversion emission spectra of the samples under 800 nm excitation at the pump power of 970 GW/cm2 at 298 K; (b) Multiphoton up-conversion emission spectra of bulk-1 with femtosecond laser excitation from 800 to 1900 nm at 298 K, inset shows optical photographs of 3rd harmonic generation at different excitation wavelength; (c) Threshold energy of 235 nm up-conversion emission with various femtosecond laser excitation.

Fig. 2a shows the up-conversion PL spectra of the samples under 800 nm femtosecond laser excitation at 298 K. It is noted that the PL intensity of bulk-1 is stronger than that of the other samples. This result is consistent with that given in Fig. 1d. Fig. 2b shows the emission spectra of bulk-1 under the excitation of femtosecond laser pulses with a wavelength ranging from 800 to 1900 nm at 298 K. There are two dominant peaks observed from the emission

5 ACS Paragon Plus Environment

ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 6 of 15

spectra. The emission peak at 235 nm represents the FEs emission arisen from the multiphoton excitation32. The is because the 235 nm peak shows the good power-law dependence of the 215 nm excitation power with a slope larger than 1 but small than 2, hence, the 235 nm peak is due to FEs radiative recombination (see Fig. S3). The other emission peak in Fig. 2b, which peak wavelength varies from 400 to 633 nm for the excitation wavelength changes from 1200 to 1900 nm, represents the third harmonic generation peak of the excitation source. Fig. 2c plots the excitation threshold of the 235 nm peak versus excitation wavelength of the femtosecond laser at 298 K. It is expected that higher excitation power is required to excite FEs emission with a longer excitation wavelength. Therefore, the single crystals diamonds support FEs emission under multiphoton excitation at 298 K.

Fig. 3 Schematic diagrams of (a) 8-absorption and (b) FEs emission of the single crystal diamond. Fig. 3 shows the schematic diagrams of 8-photon absorption and excitonic radiative

recombination process of the single-crystal diamonds. The dispersion curves of the optical and acoustic phonons are superimposed to the energy-band diagram of the diamonds. FEs radiative recombination from the intrinsic diamond is arisen from the generation of momentum-conserving phonons including (i) transverse acoustic (TA) phonons, 87 meV (ii) transverse optical (TO) phonons, 141 meV (iii) longitudinal optical (LO) phonons, 156 meV and (iv) TO+OΓ (two-phonon involving TO + Raman phonon, 141 + 159 meV). The FE emission energy, FEphoton, related to the phonon components can be defined as:    ,      

6 ACS Paragon Plus Environment

(1)

Page 7 of 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

where  ,   is the indirect bandgap of diamond,  is the binding energy of exciton,  is the phonon energy and the subscript ‘phonon‘ represents either TA, TO, LO or TO+OΓ.

Fig. 4. Emission spectra measured from bulk-1 at various temperatures with excitation wavelength equal to (a) 800, (c) 1200, and (e) 1900 nm; raw and fitted data at 77 K excited at (b) 800 nm, (d) 1200 nm, (f) 1900 nm.

Figs. 4a, 4c, and 4e show the emission spectra of bulk-1 versus temperature under femtosecond laser pulses excitation with an excitation wavelength of 800, 1200 and 1900 nm, respectively. Figs. 4b, 4d, and 4f plot the Gaussian curve fitting of the emission spectra measured at 77 K with an excitation wavelength of 800, 1200 and 1900 nm, respectively. From the low-temperature measurement, the emission peaks labeled as FETA (5.337-5.347 eV), FETO (5.286-5.290 eV), and FETO+OΓ (5.129-5.135 eV) are referred to free excitons interaction with the emission of (i) transverse acoustic (TA) phonons, (ii) transverse optical acoustic (TO) phonons and (iii) TO phonons together with the emission of an optical phonon (OΓ) respectively (Fig. 3a and 3b). Besides, a new peak located at 5.176-5.182 eV can be found at 77 K, which is probably attributed to bound exciton with longitudinal optical (LO) phonons generation.33 The emission spectra of bulk-1 versus temperature at an excitation wavelength of 800, 1200 and 1900 nm are also measured (Fig. S4). The maximum intensity 7 ACS Paragon Plus Environment

ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

of FETO is located at about 143 K for different excitation wavelength, which is very similar to that at 150 K reported in the literature.26, 34-35 The FETO band for 800 nm, 1200 nm, and 1900 nm excitation shifted to a shorter wavelength by 2.17, 3.886 and 2.757 meV, respectively as the temperature increases from 77 to 183 K. The dependence of FETO intensity on the temperature under multiphoton excitation is similar to that of the diamonds under down conversion excitation.2, 26 Hence, these confirm that multiphoton absorption is realized in the single crystal diamonds.

Fig. 5. Emission spectra measured from bulk-1 diamond single crystal versus pump energy with excitation at (a) 800 nm; (b) 1200 nm; (c) 1900 nm; the inset is the log-log curve of the normalized emission intensities versus the normalized excitation power. The slopes, n, of the linear fitted solid red lines to the measured data revealed the number of photons involved in the excitation process. Z-scan results of a 1 mm bulk-1 thick diamond single crystal with excitation wavelength equal to d) 800, e) 1200, and f) 1900 nm. The solid lines are the 3PA, 5PA and 8PA fitted curves deduced from the Z-scan theory.

Figs. 5a, 5b and 5c plot the emission spectra at various excitation powers with an excitation wavelength of 800, 1200, and 1900 nm, respectively at 298 K. The inset shows the corresponding FE emission intensity versus excitation power in the logarithmic scale. For 8 ACS Paragon Plus Environment

Page 8 of 15

Page 9 of 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

800 and 1200 nm excitation, n is found to be 3.13 and 5.09, respectively. At 1900 nm excitation, the slope, n, of the log-log curve gives a value of ~8.05. Hence, these imply that the FEs emission is supported by three-, five- and eight-photon excitation and the excitation energy is roughly one-third, one-fifth and one-eighth respectively of the bandgap energy of diamonds. Nonlinear optical properties of the diamond single crystal can be investigated by using an open-aperture Z-scan technique (Fig. S5). Figs. 5d, 5e, and 5f show the room-temperature Zscan data of the sample excited by femtosecond laser pulses with a wavelength of 800, 1200 and 1900 nm, respectively. Expression of open-aperture Z-scan transmittance,  , via nphoton absorption can be expressed by the following formula:36 









      ∫ ℎ    ,  ,  , ψ  !  ℎ



where n is the number of photons, Ψ  # 

1% &'

×

(2)

+

 ,-+ )** ,

αn is the n-photon

absorption coefficient and the other parameters are defined in the supporting information. From (2), αn at 298 K for excitation wavelength equal to 800, 1200, and 1900 nm are calculated and summarized in Table 1. It is found that the eight-photon absorption coefficient,

α8, of the bulk-1 is found to be 1.6×10–19 cm13/GW7. The three- and five- photon absorption coefficients of the diamond are comparable with or better than ZnO36 and IPPS37 respectively, revealing that diamond may serve a promising nonlinear optical material. The experimental setup and the detailed method to calculate αn are also given in the supporting information.

3. Conclusions In conclusion, FEs emission (at 235 nm) up to eight-photon absorption is achieved from single crystal diamonds at 298 K. The realization of FEs emission is due to the low concentration of defects and impurities of the single crystal diamonds with the (100) crystalline orientation. Nonlinear optical properties of the diamonds are also investigated by using an open aperture Z-scan technique. Three-, five- and eight-photon absorption coefficients of the diamonds are found to be 1.8 ×10-2 cm3/GW2, 5×10–9 cm7/GW4 and 1.6×10–19 cm13/GW7, respectively. As the three- and five-photon absorption coefficients of the diamonds are compatible with or better than that of the other reported optical nonlinear materials37-39, the corresponding eight-photon absorption coefficient should be sufficiently

9 ACS Paragon Plus Environment

ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 10 of 15

large for the utilization as the highly nonlinear optical materials for the deep ultraviolet applications. Table 1. 3PA, 5PA and 8PA coefficients of diamond single crystal at 298 K. λ (nm)

800

1200

1900

n

3

5

8

αn

1.8 ×10–2 cm3 per GW2

5×10–9 cm7 per GW4

1.6×10–19 cm13 per GW7

αn (ref)

1.6 ×10–2 cm3 per GW2

2.2×10–11 cm7 per GW4 Ref(37)

NA

Ref(36)

4. Experimental section Synthesis and characterization of diamond: The diamond samples used in this study were high pressure and high temperature (HPHT) Ib-type (100) diamond prepared by MPCVD facility using CH4 and H2 as the source and carrier gases respectively. The pressure in the growth chamber was maintained at around 330 mbar, and the substrate temperature was set at around 950 oC. After the fabrication, the as-prepared diamond wafer was removed from the substrate by laser cutting. During this study, four samples were investigated, and they are labeled as bulk-1 to bulk-3. The microwave power of bulk-1 and bulk-2 was set to 3000 and 2900 W respectively. The corresponding flow ratio of CH4 was kept at 190 sccm and that of H2 was kept at 10 sccm. For bulk-3, the microwave power was selected at 3200 W, and the flow ratio of CH4 and H2 were set to 185 and 15 sccm respectively. The bulk-4 wafer used in the experiment is a commercial HPHT Ib-type diamond. The crystalline properties of the samples were characterized by using a Smartlab (Rigaku, USA) X-ray diffractometer at room temperature. Raman measurements of the diamond samples were conducted using an HR-800 (HORIBA, Japan) spectrometer using 488 nm argon ion laser as the excitation source. The UV–vis transmittance spectrum was recorded by UV-2550 (Shimadzu, Japan) on a spectrometer. Fourier Transform infrared spectroscopy (FTIR) spectra of the samples were measured by Vertex-70 (Bruker, Germany) equipped with a mid-band MCT-A detector (liquid nitrogen cooled, 7000-600 cm-1 spectral range). Optical characterizations of diamond single crystal: The down-conversion emission of the diamond samples were excited by a 215 nm frequency quadruplet Q-switched Nd:YAG laser 10 ACS Paragon Plus Environment

Page 11 of 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

at pulsed operation (6 ns, 10 Hz) with a beam diameter of ~0.8 cm. For the defect emission measurements, the PL spectra were collected by an HR-800 (HORIBA, Japan) spectrometer using 325 and 488 nm continuous wave lasers as the excitation sources. For femtosecond laser pulses excitation measurements, a Ti:sapphire laser (Coherent Libra) and an optical parametric amplifier (Coherent OperA Solo) were used as the excitation source to generate femtosecond pulses (≈50 fs, 1 kHz) with variable emission wavelength from 800 to 1900 nm and maximum average power of ~500 mW. The laser beam was focused by a convex lens with focal length of 100 mm on the surface of the diamond single crystal. Emission of the samples was recorded by an optical fiber, connected to a spectrum analyzer (Princeton Instrument with a resolution of 0.1 nm). For the PL measurements at a different operating temperature (i.e., varies from 77 to 298 K), the sample was loaded into a low-temperature chamber (Linkam DSC 600 temperature controlled stage) purged with liquid N2. The emitted light was collected in the same way described above. Schematic experimental setup of the Z-scan is shown in fig. S5. Briefly, the laser light from the optical parametric amplifier is split into two beams by a beam splitter. The transmitted beam is focused onto the surface of the samples to a minimum size spot of ~40 µm by a convex lens 1 with a focal length of 10 cm. The beam transmitted through the samples will be collimated to detector 1 (i.e., Thorlabs amplified PbSe photodetector) by another convex lens 2. The samples could move between lens 1 and lens 2 (i.e., Z-direction). Any fluctuation of the laser light would be detected by detector 2 (i.e., Thorlabs amplified PbSe photodetector) through the reflected beam. By dividing the signals received from detector 1 by that from detector 2, the influence of laser power fluctuation can be reduced.

Acknowledgment This work was supported by NSFC grant no. 61775187, Science and Technology Projects of Shenzhen (JCYJ20170818105010341) and HK PolyU grants (no. G-YBVJ, G-YBHG).

Supporting Information The supporting information includes Raman spectra, photoluminescence spectra excited at 325 and 488 nm, emission spectra versus temperature, and Z-scan setup. This information is available free of charge via the Internet at http://pubs.acs.org/. 11 ACS Paragon Plus Environment

ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

5. Reference (1)

Thonke, K.; Schliesing, R.; Teofilov, N.; Zacharias, H.; Sauer, R.; Zaitsev, A. M.; Kanda, H. Anthony, T. R. Electron–Hole Drops in Synthetic Diamond. Diamond Relat. Mater. 2000, 9, 428-431.

(2)

Lipatov, E. I.; Genin, D. E. e.; Grigor'ev, D. V. e. Tarasenko, V. F., Recombination Radiation in the Diamond. In Luminescence-An Outlook on the Phenomena and Their Applications. InTech: 2016.

(3)

Yokota, Y.; Tachibana, T.; Miyata, K.; Hayashi, K.; Kobashi, K.; Hatta, A.; Ito, T.; Hiraki, A. Shintani, Y. Cathodoluminescence of Boron-doped Heteroepitaxial Diamond Films on Platinum. Diamond Relat. Mater. 1999, 8, 1587-1591.

(4)

Liaugaudas, G.; Davies, G.; Suhling, K.; Khan, R. Evans, D. Luminescence Lifetimes of Neutral Nitrogen-Vacancy Centres in Synthetic Diamond Containing Nitrogen. J. Phys.: Condens. Matter 2012, 24, 435503.

(5)

Hazama, Y.; Naka, N.; Kuwata-Gonokami, M. Tanaka, K. Resonant Creation of Indirect Excitons in Diamond at the Phonon-Assisted Absorption Edge. Europhys. Lett. 2013, 104, 47012.

(6)

H. Robins, L.; N. Farabaugh, E. Feldman, A., Cathodoluminescence spectroscopy of Free and Bound Excitons in Chemical-Vapor-Deposited Diamond. 1993; Vol. 48, p 14167-14181.

(7)

Prins, J. F. Recombination Luminescence from Defects in Boron-Ion ImplantationDoped Diamond using Low Fluences. Mater. Res. Innovations 1998, 1, 243-253.

(8)

Manfredotti, C.; Fizzotti, F.; Lo Giudice, A.; Polesello, P.; Vittone, E.; Truccato, M. Rossi, P. Ion Beam Induced Luminescence Maps in CVD Diamond as Obtained by Coincidence Measurements. Diamond Relat. Mater. 1999, 8, 1592-1596.

(9)

Cleri, F.; Keblinski, P.; Colombo, L.; Wolf, D. Phillpot, S. R. On the Electrical Activity of sp 2 -Bonded Grain Boundaries in Nanocrystalline Diamond. Europhys. Lett. 1999, 46, 671.

(10) Roth, T. Laenen, R. Absorption of Free Carriers in Diamond Determined from the Visible to the Mid-Infrared by Femtosecond Two-Photon Absorption Spectroscopy. Opt. Commun. 2001, 189, 289-296. (11) Kozák, M.; Trojánek, F.; Dzurňák, B. Malý, P. Two-and Three-Photon Absorption in Chemical Vapor Deposition Diamond. JOSA B 2012, 29, 1141-1145. (12) Dadap, J.; Focht, G. B.; Reitze, D. Downer, M. C. Two-Photon Absorption in Diamond and Its Application to Ultraviolet Femtosecond Pulse-Width Measurement. Opt. Lett. 1991, 16, 499-501. (13) Trojánek, F.; Žídek, K.; Dzurňák, B.; Kozák, M. Malý, P. Nonlinear Optical Properties of Nanocrystalline Diamond. Opt. Express 2010, 18, 1349-1357. (14) Badzian, A. Badzian, T. Diamond Homoepitaxy by Chemical Vapor Deposition. Diamond Relat. Mater. 1993, 2, 147-157. (15) Achard, J.; Silva, F.; Tallaire, A.; Bonnin, X.; Lombardi, G.; Hassouni, K. Gicquel, A. High Quality MPACVD Diamond Single Crystal Growth: High Microwave Power Density Regime. J. Phys. D: Appl. Phys. 2007, 40, 6175.

12 ACS Paragon Plus Environment

Page 12 of 15

Page 13 of 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

(16) Schwarz, S.; Rottmair, C.; Hirmke, J.; Rosiwal, S. Singer, R. F. CVD-Diamond SingleCrystal Growth. J. Cryst. Growth 2004, 271, 425-434. (17) Sakaguchi, I.; Nishitani-Gamo, M.; Loh, K. P.; Haneda, H. Ando, T. Hydrogen Incorporation Control in High Quality Homoepitaxial Diamond (111) Growth. Diamond Relat. Mater. 1999, 8, 1291-1295. (18) Tajani, A.; Mermoux, M.; Marcus, B.; Bustarret, E.; Gheeraert, E. Koizumi, S. Strains and Cracks in Undoped and Phosphorus‐Doped {111} Homoepitaxial Diamond Films. Phys. Status Solidi A 2003, 199, 87-91. (19) Samlenski, R.; Schmälzlin, J.; Brenn, R.; Wild, C.; Müller-Sebert, W. Koidl, P. Characterization of Homoepitaxial Diamond Films by Nuclear Methods. Diamond Relat. Mater. 1995, 4, 503-507. (20) Samlenski, R.; Haug, C.; Brenn, R.; Wild, C.; Locher, R. Koidl, P. Characterisation and Lattice Location of Nitrogen and Boron in Homoepitaxial CVD Diamond. Diamond Relat. Mater. 1996, 5, 947-951. (21) Benea, I. C. Rosczyk, B. R. Crystallographic Defects and Mechanical Strength of Micron Size Monocrystalline Diamond. Intertech, Baltimore, MD, USA 2013. (22) Mollart, T.; Lewis, K.; Pickles, C. Wort, C. Factors Affecting the Optical Performance of CVD Diamond Infrared Optics. Semicond. Sci. Technol. 2003, 18, S117. (23) Rosczyk, B.; Onyenemezu, C. Benea, I., Study on Crystalline Structure (Crystallite Size) and Fracture Mode of Micron Diamond Particles under Applied Shear Stress. The Effect on Performance in Lapping of Sapphire. 2013. (24) Kanda, H.; Akaishi, M. Yamaoka, S. Synthesis of Diamond with the Highest Nitrogen Concentration. Diamond Relat. Mater. 1999, 8, 1441-1443. (25) Woods, G. S.; Van Wyk, J. A. Collins, A. T. The Nitrogen Content of Type Ib Synthetic Diamond. Philos. Mag. B 1990, 62, 589-595. (26) Robins, L. H.; Farabaugh, E. N. Feldman, A. Cathodoluminescence Spectroscopy of Free and Bound Excitons in Chemical-Vapor-Deposited Diamond. Phys. Rev. B 1993, 48, 14167. (27) Lawson,

S.

C.;

Kanda,

H.;

Kiyota,

H.;

Tsutsumi,

T.

Kawarada,

H.

Cathodoluminescence from High ‐ Pressure Synthetic and Chemical ‐ Vapor ‐ Deposited Diamond. J. Appl. Phys. 1995, 77, 1729-1734. (28) Manfredotti, C.; Fizzotti, F.; Giudice, A. L.; Polesello, P.; Vittone, E.; Truccato, M. Rossi, P. Ion Beam Induced Luminescence Maps in CVD Diamond as Obtained by Coincidence Measurements. Diamond Relat. Mater. 1999, 8, 1592-1596. (29) Cleri, F.; Keblinski, P.; Colombo, L.; Wolf, D. Phillpot, S. On the Electrical Activity of sp2-Bonded Grain Boundaries in Nanocrystalline Diamond. Europhys. Lett. 1999, 46, 671. (30) Acosta, V.; Bauch, E.; Ledbetter, M.; Santori, C.; Fu, K.-M.; Barclay, P.; Beausoleil, R.; Linget, H.; Roch, J. Treussart, F. Diamonds with a High Density of Nitrogen-Vacancy Centers for Magnetometry Applications. Phys. Rev. B 2009, 80, 115202. (31) Meng, Y.-f.; Yan, C.-s.; Lai, J.; Krasnicki, S.; Shu, H.; Yu, T.; Liang, Q.; Mao, H.-k. Hemley, R. J. Enhanced Optical Properties of Chemical Vapor Deposited Single 13 ACS Paragon Plus Environment

ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Crystal Diamond by Low-Pressure/High-Temperature Annealing. Proc. Natl. Acad. Sci. U.S.A. 2008, 105, 17620-17625. (32) He, H.; Yu, Q.; Li, H.; Li, J.; Si, J.; Jin, Y.; Wang, N.; Wang, J.; He, J.; Wang, X.; Zhang, Y. Ye, Z. Exciton Localization in Solution-Processed Organolead Trihalide Perovskites. Nat. Commun. 2016, 7, 10896. (33) Sharp, S.; Collins, A.; Davies, G. Joyce, G. Higher Resolution Studies of Shallow Bound Exciton Luminescence in Diamond. J. Phys.: Condens. Matter 1997, 9, L451. (34) Takiyama, K.; Abd-Elrahman, M.; Fujita, T. Oda, T. Photoluminescence and Decay Kinetics of Indirect Free Excitons in Diamonds under the Near-Resonant Laser Excitation. Solid State Commun. 1996, 99, 793-797. (35) Fujii, A.; Takiyama, K.; Maki, R. Fujita, T. Lifetime and Quantum Efficiency of Luminescence due to Indirect Excitons in a Diamond. J. Lumin. 2001, 94, 355-357. (36) Gu, B.; Huang, X.-Q.; Tan, S.-Q.; Wang, M. Ji, W. Z-scan Analytical Theories for Characterizing Multiphoton Absorbers. Appl. Phys. B 2009, 95, 375-381. (37) He, J.; Qu, Y.; Li, H.; Mi, J. Ji, W. Three-Photon Absorption in ZnO and ZnS Crystals. Opt. Express 2005, 13, 9235-9247. (38) Zheng, Q.; Zhu, H.; Chen, S.-C.; Tang, C.; Ma, E. Chen, X. Frequency-Upconverted Stimulated Emission by Simultaneous Five-Photon Absorption. Nat. Photonics 2013, 7, 234-239. (39) Chen, W.; Bhaumik, S.; Veldhuis, S. A.; Xing, G.; Xu, Q.; Grätzel, M.; Mhaisalkar, S.; Mathews, N. Sum, T. C. Giant Five-Photon Absorption from Multidimensional CoreShell Halide Perovskite Colloidal Nanocrystals. Nat. Commun. 2017, 8, 15198.

14 ACS Paragon Plus Environment

Page 14 of 15

Page 15 of 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

Table of contents

Room temperature up-conversion emission up to eight-photon absorption is demonstrated from diamond single crystals with low concentration of defects and impurities.

15 ACS Paragon Plus Environment