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Optical and facet dependent carrier recombination properties of hendeca-facet InGaN/GaN micro light emitters Sunyong Hwang, Nam Han, Hokyeong Jeong, Jun-Hyuk Park, Seung-Hyuk Lim, JongHoi Cho, Yong-Hoon Cho, Hyeon Jun Jeong, Mun Seok Jeong, and Jong Kyu Kim Cryst. Growth Des., Just Accepted Manuscript • DOI: 10.1021/acs.cgd.6b01889 • Publication Date (Web): 30 May 2017 Downloaded from http://pubs.acs.org on June 8, 2017

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Crystal Growth & Design

Cover page Optical and facet dependent carrier recombination properties of hendeca-facet InGaN/GaN micro light emitters Sunyong Hwang,† Nam Han,† Hokyeong Jeong,† Jun Hyuk Park,† Seung-Hyuk Lim,‡ JongHoi Cho,‡ Yong-Hoon Cho,‡ Hyeon Jun Jeong,§ Mun Seok Jeong,§ and Jong Kyu Kim*,† †

Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea

‡

Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea

§

Center for for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 16419, Republic of Korea

Abstract A hendeca-facet (HF) micro light emitter based on InGaN/GaN multiple quantum well (MQW) is grown via selective area metal-organic chemical vapor deposition. The HF micro light emitter is found to possess four crystallographic facets, (0001), {1-101}, {11-22}, and {11-20}. Distinct facet-dependent emission properties, investigated by confocal scanning photoluminescence (PL) and cathodoluminescence (CL) measurements, are found to originate from differences in indium composition and InGaN quantum well thickness of the MQW. Facet-dependent recombination properties, examined by temperature-dependent micro-PL and PL streak images, suggest that the localization energy and non-radiative recombination of carriers at MQW on each facet are varied with the polarization fields and threading dislocations. Besides, scanning time resolved PL measurements reveal that the recombination lifetime around the edge where different facets meet is shorter than that in the facet regions, implying such non-radiative recombination can be a significant obstacle for achieving high quantum efficiency micro-structured light-emitting diodes.

Corresponding Author Prof. Jong Kyu Kim Address: Pohang University of Science and technology (POSTECH) Department of Materials Science and Engineering Eng. Bldg. 1, #215 Pohang city, 37673, Republic of Korea Tel: 82-54-279-2149 Fax: 82-54-279-2399 E-mail: [email protected]

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Optical and facet dependent carrier recombination properties of hendeca-facet InGaN/GaN micro light emitters Sunyong Hwang,† Nam Han,† Hokyeong Jeong,† Jun Hyuk Park,† Seung-Hyuk Lim,‡ JongHoi Cho,‡ Yong-Hoon Cho,‡ Hyeon Jun Jeong,§ Mun Seok Jeong,§ and Jong Kyu Kim*,† †

Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea

‡

Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea

§

Center for for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 16419, Republic of Korea

*Corresponding author e-mail: [email protected]

Abstract A hendeca-facet (HF) micro light emitter based on InGaN/GaN multiple quantum well (MQW) is grown via selective area metal-organic chemical vapor deposition. The HF micro light emitter is found to possess four crystallographic facets, (0001), {1-101}, {11-22}, and {11-20}. Distinct facet-dependent emission properties, investigated by confocal scanning photoluminescence (PL) and cathodoluminescence (CL) measurements, are found to originate from differences in indium composition and InGaN quantum well thickness of the MQW. Facet-dependent recombination properties, examined by temperature-dependent micro-PL and PL streak images, suggest that the localization energy and non-radiative recombination of carriers at MQW on each facet are varied with the polarization fields and threading dislocations. Besides, scanning time resolved PL measurements reveal that the recombination lifetime around the edge where different facets meet is shorter than that in the facet regions, implying such non-radiative recombination can be a significant obstacle for achieving high quantum efficiency micro-structured light-emitting diodes.


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1. Introduction III-nitrides have been regarded as fascinating materials system for highly efficient light-emitting diodes (LEDs) covering a wide range of wavelengths from visible to deep ultraviolet.1-2 Conventional InGaN-based multiple quantum well (MQW) LEDs grown along Ga-polar (0001) orientation have evolved into a pervasive commercial success, however, are susceptible to the strong internal electric field induced by the spontaneous and the piezoelectric polarization.3 The strong energy band bending in the MQW grown on the polar (0001) plane by the strong electric field causes detrimental problems in LED performance; a spatial separation of electrons and holes in the quantum wells (QWs) causing a low radiative recombination efficiency, a reduced effective width of QWs resulting in a pronounced nonradiative Auger recombinations, and a reduced effective barrier height facilitating the carrier leakage.4-6 In order to address these challenges caused by the polar orientation, substantial effort have been made for homoepitaxial growth of III-nitrides along non-polar and semipolar crystallographic orientations on bulk GaN substrates.7,8 Despite very promising reports of high-performance LEDs and laser diodes, non-polar and semi-polar GaN substrates are presently very small in size and costly, which calls for a viable pathway for non-polar and semi-polar InGaN/GaN heteroepitaxial structures on large area, cost-effective substrates. Recently, InGaN-based three-dimensional (3D) micro-structures have attracted much attention to obtain non-polar and semi-polar heteroepitaxial structures on conventional cplane sapphire substrates by selective area growth (SAG) method.9,10 Various designs of micro-structured InGaN/GaN LEDs, including pyramid,11,12 stripe,13 micro-donut,14,15 and double concentric truncated pyramid structures16 with non-polar and semi-polar facets have been suggested to overcome the challenges caused by the induced polarization as well as by the bulk GaN substrates simultaneously. In addition, the 3D micro-structured LEDs exhibit high light extraction efficiency due to suppressed total internal reflection loss,17 and potential to generate panchromatic white light without phosphor coating process enabled by different In incorporation and thickness along different facets. Nevertheless, the carrier recombination properties of individual crystallographic facets, edges, and corners constituting such 3D micro-structured LEDs, which are critical to find the strategy to realize highly efficient white light emitters, have not been systematically investigated. In this study, hendeca-facet (HF) micro light emitters containing InGaN/GaN MQWs on various crystallographic planes including polar (0001), semi-polar {1-101} and {11-22}, and non-polar {11-20} were grown by SAG by using metal-organic chemical vapor



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deposition (MOCVD) to investigate facet-dependent optical properties. The structural features of the HF light emitter were characterized by using scanning electron microscopy (SEM) and cross-section transmission electron microscopy (TEM). Microscopic optical characterizations were performed by means of cathodoluminescence (CL), temperaturedependent micro-photoluminescence (PL), and confocal scanning PL. In addition, PL streak images were taken to investigate the transient carrier dynamics of the HF light emitters. We found that the carrier recombination properties and PL efficiency of the HF light emitter InGaN/GaN MQW are mainly affected by crystallographic orientation of the facet and its geometry within the facets.

2. Experimental Section MOCVD Growth of HF micro light emitters. A 200 nm of SiO2 layer was deposited by plasma-enhanced chemical vapor deposition on an MOCVD-grown n-GaN/sapphire template. A 3 µm × 20 µm rectangles along GaN direction were patterned by conventional photolithography, followed by dry etching to expose the n-type GaN rectangles. Regrowth of HF light emitter on such substrate was performed by MOCVD. During the SAG of n-type HF-GaN, MOCVD reactor pressure of 200 mbar, V/III ratio of 152, and the growth temperature of 1100 °C were maintained. Then, 5 pairs of InGaN/GaN MQWs were conformally grown on the n-type HF GaN. InGaN quantum well growth was performed at 724 °C with V/III ratio of 11700 under nitrogen atmosphere. After the growth of the MQW, Mg-doped p-GaN layer was grown at 970 °C under 200 mbar. With the growth condition, consistent HF structures could be grown at different times.

Structural Characterization. Scanning electron microscopy (SEM) measurement was done with field-emission SEM (Philips XL30S FEG), operated at 5 kV. For transmission electron microscopy (TEM) measurements, the focused ion beam (FIB) method is employed for the sample preparation, and Cs-corrected TEM (Titan Cubed G2 60−300) was employed with an operating voltage of 200 kV.

Characterization of MQW Emission Properties. CL measurement was performed at room temperature with Gatan MonoCL4 equipped with SEM, where the acceleration voltages was 15 kV. For confocal scanning micro-PL and scanning time resolved PL (TRPL)


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measurements of HF light emitter, NTEGRA, NT-MDT was employed. For the excitation of the confocal scanning micro-PL, a 405 nm continuous-wave laser diode was employed. For scanning TRPL measurement, a pulsed 405 nm laser with a repetition rate of 80 MHz and a time-correlated single photon counting (TCSPC) was used. A high-speed photomultiplier tube detector (PMC-100, Photonic Solution) was applied for TCSPC photon counting. Micro-PL measurement was performed from 10K to 295K with the 405 nm continuous-wave laser diode. The laser beam was placed on (0001) and {11-22} surfaces for the measurement with ~1 µm beam spot diameter. Laser power was changed from 2 µW to 2.5 mW. For PL streak image measurement, a frequency-doubled (405 nm) mode-locked Ti:sapphire laser with a repetition rate of 80 MHz with ~150 µm beam spot diameter was used, and a cryogenic system was utilized to control the measurement temperature from 16K to 295K. A streak camera (Hamamatsu, C7700-01) was employed to measure the decay lifetime.

3. Results and Discussion HF micro light emitters with 5 pairs of InGaN/GaN MQW were grown on c-plane sapphire substrates by MOCVD using SiO2 growth mask with rectangular openings. Figure 1 shows SEM images of the grown HF light emitter. As shown in 45° tilt-view and top-view images, the HF light emitter has four different crystallographic facets, i.e., one (0001), six {1101}, two {11-22} and two {11-20}. The HF micro structure contains polar (0001) facet, semi-polar {1-101}, {11-22} facets, and non-polar {11-20} facets, which can be easily achieved by simple rectangular opening along the direction on a c-plane sapphire substrate with relatively large area, thus useful and important for analyzing the facetdependent optical properties. Note that the geometric structure of the HF light emitter can be modified by varying the geometry of growth mask and MOCVD growth conditions. Optical properties of the HF light emitter InGaN/GaN MQW were investigated by both CL and confocal scanning PL microscopy measurements. Figure 2a shows top-view panchromatic CL image of the HF light emitter with acceleration voltage of 15 kV at room temperature. The emission from the SiO2 growth mask region originates from the underlying n-type GaN template. To clarify the facet-dependent emission properties of the HF light emitter, monochromatic CL images were taken at two distinct peak wavelengths, 438 nm and 490 nm, of the panchromatic spectrum, as shown in Figure 2b,c. It is found that the emission near 438 nm originates from the MQW on {11-22} facet. Although the longer emission near



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490 nm is expected to be dominant from (0001) MQW,18,19 it is detected over the whole HF light emitter structure including {11-22} and {1-101} facets, which is presumably attributed to the excitation of not only the InGaN QWs but also the GaN layer causing defect-related yellow emission as shown in the panchromatic CL spectrum shown in Figure S1a. Confocal scanning PL microscopy measurements with excitation wavelength of 405 nm were performed to exclude the effect of the strong yellow emission from the GaN layer, thereby properly showing emission properties of the long-wavelength emission from the (0001) facet. Figure 2d exhibits the peak emission wavelength map obtained from the measurement. Distinctive peak wavelengths among facets are clearly found, where the peak wavelengths from (0001), {1-101}, and {11-22} facets are ~478 nm, ~465 nm, and ~440 nm, respectively. Note that the vertical geometry of non-polar {11-20} facets to the substrate made it very difficult to measure PL spectrum by using the scanning PL spectroscopy from the top side. For clear investigation of facet-dependent emission properties, PL intensity maps with the emission wavelengths of 440 nm and 478 nm are plotted as shown in Figure 2e, f. The two emission wavelengths were selected as they are the two representative peak wavelengths from the {11-22} and the (0001) facets. Strong short wavelength emission ~ 440 nm is dominant from the {11-22} facets, while, long wavelength emission ~ 490 nm is dominant from the (0001) facet. The PL emission from the {1-101} facet is relatively weak compared to those from (0001) and {11-22} facets, which can be attributed to much thinner MQW active layer (See table S1) and a larger defect density causing a predominant yellow emission (See Figure S1b). The (0001) and {11-22} facets, which are representative polar and semi-polar planes, have distinctive emissions from both PL and CL, thus, were focused on for further investigation. To investigate the origin of the different emission properties between MQWs on the (0001) and the {11-22} facets of the HF light emitter, high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and TEM energy dispersive spectroscopy (EDS) of InGaN/GaN MQWs across cross-sections were performed. Figure 3 shows the cross-sectional STEM images, where the insets A and B depict the enlarged images of the MQWs on (0001) and {11-22} facets, respectively, marked by red circles. In the magnified MQW STEM images, bright layers represent InGaN QWs, while the dark layers are GaN quantum barriers (QBs). To clarify the atomic composition of the MQW layers, TEM-EDS measurements were performed for these magnified MQW regions. Table 1 shows thickness and indium composition of QW layers obtained from STEM intensity and indium


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composition profiles across MQW layers. It is noted that the QWs on (0001) are thicker with higher indium composition than the QWs on {11-22}, which is the reason for the longer emission wavelength of the (0001) MQW.15 STEM images, thickness and In compositions of QWs on {11-22} and {1-101} facets are shown in supporting information, Fig. S2 and Table S1. Temperature-dependent optical properties at the (0001) and the {11-22} facets were characterized by micro-PL measurements. Figure 4a shows integrated PL intensities of MQWs on (0001) and {11-22} facets as a function of reciprocal temperature. Assuming the internal quantum efficiency (IQE) at cryogenic temperature is unity, the integrated PL intensities at both facets show exponential decrease in IQE with increasing temperature, which can be fitted by the following Arrhenius function, =

0 1 + exp − + exp −

where I(0) is the integrated PL intensity at cryogenic temperature, E1 is the exciton binding energy with impurities, and E2 is the localization energy in active region. A1 and A2 are weighting constants, which are related with density of impurities and non-radiative recombination center, respectively.20,21 The fitting results shown by line profiles in Figure 4a are consistent with the experimentally acquired integrated PL intensity values. Table 2 shows fitted A1, A2, E1, and E2 values for the MQWs on (0001) and {11-22} facets, which matches to previously reported exciton binding energies and localization energies.20,22 A1 of the semi-polar {11-22} facet is larger than that of the polar (0001) facet, presumably implying that more impurities are incorporated into the {11-22} facet MQW, as previously reported.23 In addition, A2 of the (0001) facet is ~9 times larger than that of the {11-22} facet, indicating the (0001) facet has larger density of non-radiative recombination centers than the {11-22} facet, which originates from the threading dislocation (TD) propagation through the opening region of SiO2 growth mask. On the contrary, the {11-22} facet includes less TDs than the (0001) facet, because SiO2 growth mask effectively blocks the propagation of TDs from the underlayer.24 Carrier localization energies (E2) of MQW on (0001) and {11-22} are 54.1 and 49.9 meV, respectively, where the higher localization energy on (0001) is presumably due to the larger indium segregation of the InGaN QW than that on {11-22}. Laser power-dependent micro-PL measurements for the same regions were also



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performed under the same temperature range. Blue-shift of the peak wavelength as large as 31 nm with increasing laser power from 2 µW to 2.5 mW was found at the MQW on the (0001) facet, while the one on the {11-22} didn’t exhibit noticeable peak-shift as shown in Figure S3. This is attributed to the difference in carrier screening effect on both facets where the larger polarization field exists on the polar (0001) facet than the semi-polar {11-22} facet.25 Figure 4b presents normalized PL efficiency at 200 K as a function of carrier generation rate at the MQW, where the carrier generation rate G is estimated by using = 1 − / ! ℎ#, where Plaser is the optical power incident on the sample, R is the Fresnel reflection at the sample surface, α is the absorption coefficient of the InGaN quantum well at 405 nm, Aspot is the area of the laser spot on the sample surface, and hν is the energy of a 405 nm photon. When estimating R and Aspot, the tilt-angle of the {11-22} surface to the (0001) surface of 58.4° is considered. The absorption coefficient α is calculated by using its square-root dependence on energy.26 The MQW on both the polar (0001) and the semi-polar {11-22} facets exhibit efficiency droop behavior as G increases. The PL efficiency on the polar (0001) facet has efficiency droop as large as 16%, while the PL efficiency droop on the semi-polar {11-22} is ~9% at G of 5 × 1026 cm-3s-1. (See Fig. S4 in the supporting information for more data) This difference in PL efficiency droop behavior between the two different facets is attributed to the following reasons. First, the indium composition of the InGaN QW on each facet is different. Due to adsorption and desorption kinetics of precursors on the 3D GaN micro-structure, the MQW on the (0001) facet has larger indium composition and thicker QW than the MQW on the {11-22} facet as shown in Table 1, consistent with previous studies.11,12,15,16,19 The higher indium composition in the InGaN QW, the larger its Auger recombination coefficient and polarization-induced electric field, leading to more efficiency droop.4 Second, electron and hole wave functions in the conduction and the valence bands in the MQW are separated and confined at the QW edge, more on the polar (0001) facet than the semi-polar {11-22} facet due to the stronger polarization field and thicker QWs. Therefore, Auger recombination of carriers at the (0001) QW is more severe than the {11-22} QW under the same carrier concentration.27 To investigate the transient carrier dynamics for the HF light emitter, PL streak images of the structure were obtained from 16 K to 295 K. Figure 5a,b depict the obtained image and the insets exhibit the TRPL curves for 440 nm (dominant emission from semi-polar {11-22}


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facet) and 463 nm (from the polar (0001) facet) at 16 K and 295 K. By employing two exponential curve fitting to the TRPL curves, fast and slow decay times, and pre-exponential coefficient ratios for the two facets were estimated. Fast decay time is related to the escape of carriers to the non-radiative recombination centers, and slow decay time is related to the radiative recombination of carriers.28 Figure 5c shows temperature dependent fast and slow decay times for 440 nm and 463 nm emissions. Fast decay times for both facets do not show remarkable difference, but slow decay times for the facets show different behaviors. Slow decay time for the (0001) 463 nm emission is longer than the {11-22} 440 nm emission, which is attributed to the smaller electron-hole wave functions overlap that originates from the polarization field and QW structure with higher indium composition and thicker QW at the (0001) facet. To further analyze the facet-dependent transient properties, scanning TRPL measurements of HF light emitter for both the (0001) and the {11-22} emissions were performed. Figure 6a,b show the PL lifetime maps of the HF light emitter, with the respective emission facets highlighted: the (0001) for the 478 nm, and the {11-22} for the 440 nm emission. In both cases, the lifetime distribution within each facet is not uniform, which is attributed to both indium composition variation and local variation of the non-radiative recombination centers. It is observed that the lifetime gets shorter in the edge regions, implying that the non-radiative recombination is severe around the edge region. The microscopic characterizations of HF light emitters reveal that the polarization field at each facet and the TD distributions through the micro-structure are the significant factors affecting the properties of micro-structured InGaN/GaN LEDs. For high quantum efficiency devices, the geometric structure and TD distribution of selectively grown GaN should be properly tuned by optimizing the geometry of growth mask and MOCVD growth conditions. Besides, severe non-radiative recombinations at the edge regions should be considered to increase quantum efficiency of such micro-structured GaN LED devices. Those edge areas may also work as electron leakage source, largely reducing the quantum efficiency, therefore improving the crystal quality and introducing the passivation layer in the edge region for electrically-driven HF light emitters would be needed.29 Although the HF emitter did not show white emission, we believe that our experimental results give strategic guides toward high quantum efficiency panchromatic light emitters by using 3D micro-structured GaN by optimizing MOCVD growth condition to incorporate In into different facets with appropriate composition, thickness, and high crystal quality.



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4. Conclusions We presented HF light emitter InGaN/GaN MQW by using SAG of MOCVD on rectangular patterned growth mask, and systematically investigated their structural and optical properties. SEM and TEM images of the structure revealed that the grown structure has 11 facets with four different crystallographic orientations of (0001), {11-22}, {11-20}, and {1-101}. InGaN/GaN MQW on the polar (0001) facet has longer emission wavelength than the semi-polar {11-22} and {1-101} facets, which is due to the different indium composition and InGaN QW thickness in the MQW. Furthermore, temperature-dependent micro-PL and carrier generation rate dependent PL efficiency behaviors on (0001) and {11-22} facets were investigated. Different recombination properties of MQWs on those facets originate from the polarization fields of MQW direction and TD distributions. TRPLs of HF light emitter extracted from PL streak images reveal that the slow lifetime is longer on the polar (0001) facet, also due to the polarization field. Non-radiative recombinations are found to be dominant on edge regions where two different facets meet, thereby reducing quantum efficiency of the micro-structured device.

ASSOCIATED CONTENT Supporting Information Cathodoluminescence (CL) measurement of HF light emitter structure (Figure S1), HADDFSTEM measurement of HF light emitter (Figure S2), Facet-dependent micro-PL measurement (Figure S3), PL efficiency droop of MQW on (0001) and {11-22} facets of HF micro light emitter (Figure S4). This material is available free of charge via the Internet at http://pubs.acs.org/.

AUTHOR INFORMATION Corresponding Author *E-mail: [email protected]


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Figures

Figure 1. Scanning electron microscopy (SEM) images of the grown HF light emitter. (a) 45° tilt-view, and (b) top-view image. Different colors for (0001), {11-22}, {1-101}, and {11-20} facets are expressed on the images.



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Figure 2. (a)~(c) Cathodoluminescence (CL) images, and (d)~(f) Confocal scanning microscopy images of HF light emitter. (a) Panchromatic image of HF light emitter, and monochromatic images of the structure at (b) 438 nm and (c) 490 nm. (d) Confocal PL peak wavelength mapping, and PL intensity mapping at (e) 440 nm and (f) 478 nm of HF light emitter. Scale bar represents 5μm.


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Figure 3. Cross-section HAADF-STEM image of HF light emitter image across direction. Top-left inset shows top-view SEM of HF light emitter with focused ion beam (FIB) milling region marked by red dashed line. Inset A and B depict the magnified STEM images of MQW regions on (0001) and {11-22} facets. Scale bar of the inset is 20 nm.



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Figure 4. Temperature dependent micro-PL results measured at (0001) and {11-22} facets. (a) Integrated PL intensity of MQW emissions as a function of reciprocal temperature. (b) Carrier generation rate (G) dependent normalized PL efficiencies of HF light emitter at (0001) and {11-22} facets.


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Figure 5. Streak images of HF light emitter measured at (a) 16 K and (b) 295 K. Insets represent the time-resolved PL at 440 nm and 463 nm, extracted from each streak image. (c) Temperature dependent fast and slow decay lifetimes at 440 nm and 463 nm.



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Figure 6. Confocal scanning TRPL mapping of HF light emitter measured at (a) 478 nm and (b) 440 nm. (0001) and {11-22} facets are highlighted in each figure, and insets show corresponding facets on top-view SEM images.


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Tables QW1

QW2

QW3

QW4

QW5

Thickness

(0001)

9.48

8.72

8.06

8.06

8.06

(nm)

{11-22}

3.29

3.19

3.00

2.68

2.49

Indium

(0001)

21.5

23.6

23.1

23.1

24.0

comp. (%)

{11-22}

14.1

13.3

12.9

13.2

11.7

Table 1. Thickness and indium composition of quantum wells at (0001) and {11-22} facets. Growth direction from QW1 to QW5 as shown in Fig 3.



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A1

E1 (meV)

A2

E2 (meV)

(0001)

1.79

4.57

59.3

54.1

{11-22}

4.92

6.95

6.83

49.9

Table 2. Arrhenius fitting results of temperature dependent PL intensities at (0001) and {1122} facet.


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For Table of Contents Use Only Optical and facet dependent carrier recombination properties of hendeca-facet InGaN/GaN micro light emitters Sunyong Hwang,† Nam Han,† Hokyeong Jeong,† Jun Hyuk Park,† Seung-Hyuk Lim,‡ JongHoi Cho,‡ Yong-Hoon Cho,‡ Hyeon Jun Jeong,§ Mun Seok Jeong,§ and Jong Kyu Kim*,† †

Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea ‡ Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea § Center for for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 16419, Republic of Korea Corresponding Author *E-mail: [email protected]

A hendeca-facet (HF) light emitter based on InGaN/GaN multiple quantum well (MQW) is grown via selective area metal-organic chemical vapor deposition. The HF light emitter is found to possess four crystallographic facets, (0001), {1-101}, {11-22}, and {1120}. Distinct facet-dependent emission properties are found to originate from differences in indium composition and thickness of the MQW.


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Optical and Facet-Dependent Carrier ... - ACS Publications

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