LETTER pubs.acs.org/NanoLett
n-InAs Nanopyramids Fully Integrated into Silicon Slawomir Prucnal,*,†,‡ Stefan Facsko,† Christine Baumgart,† Heidemarie Schmidt,† Maciej Oskar Liedke,† Lars Rebohle,† Artem Shalimov,† Helfried Reuther,† Aloke Kanjilal,† Arndt M€ucklich,† Manfred Helm,† Jerzy Zuk,‡ and Wolfgang Skorupa† †
Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden, Germany ‡ Maria Curie-Sklodowska University, Pl. M. Curie-Sklodowskiej 1, 20-035 Lublin, Poland ABSTRACT: InAs with an extremely high electron mobility (up to 40 000 cm2/V s) seems to be the most suitable candidate for better electronic devices performance. Here we present a synthesis of inverted crystalline InAs nanopyramids (NPs) in silicon using a combined hot ion implantation and millisecond flash lamp annealing techniques. Conventional selective etching was used to form the InAs/Si heterojunction. The currentvoltage measurement confirms the heterojunction diode formation with the ideality factor of η = 4.6. Kelvin probe force microscopy measurements indicate a type-II band alignment of n-type InAs NPs on p-type silicon. The main advantage of our method is its integration with large-scale silicon technology, which also allows applying it for Si-based electronic devices. KEYWORDS: Heterojunction, flash lamp annealing, InAs, heteronanowires, silicon
T
he downscaling and stressor technology of Si-based devices is extending the performance of the silicon channel to its limits. The replacement of standard SiO2 gate dielectric by high-k materials helps to follow the Moore’s law for the next few years. For further enhancement of the device speed the integration of IIIV compound semiconductors with silicon is unavoidable. The InAs nanostructure combined with the silicon platform seems to be the most promising for tunnel field effect transistors (TFET) operating at low voltage ( 0) between the back gold contact 2817
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Nano Letters and the top of the InAs nanocolumn (see inset Figure 6) via a conductive tip. Figure 6 shows room temperature currentvoltage (IV) characteristic obtained from the InAs/p-Si heterojunction. The investigated structures consist of about 60 nm in diameter InAs nanopyramids on 100 nm high silicon fingers. The average pn junction area between the InAs NP and the silicon finger is in the range of 700 nm2. The measured currentvoltage curves showed typical diode behavior. When the positive bias voltage is applied to the Au bottom electrode (V > 0 in Figure 6), the current increases exponentially up to 300 nA, which is the maximum measurable current value in our system. The measured IV data correspond to the IV characteristics of heterojunction diode with the ideality factor η = 4.6. The high value of the ideality factor can be related to defects at the heterojunction resulting in recombination centers and PooleFrenkel conduction.20 The inset in the left top corner of Figure 6 shows a SEM image of the FLA and the etched sample used for IV measurements. The InAs NPs placed on silicon fingers are clearly visible as bright spots. In summary, InAs nanopyramids on Si fingers were formed by ion implantation, flash lamp annealing, and wet chemical etching, leading to an InAs/Si heterojunction. It is shown that IIIV semiconductors can be fully integrated into the silicon technology. The presented experiments prove the high-quality InAs nanocrystal formation in silicon. Measurements demonstrate that the n-type InAs NP are degenerate with a type-II band alignment of InAs-Si system. The IV characteristics confirm the InAs/p-Si heterojunction diode formation. Here we have used InAs as the active material, but other compound semiconductors could be explored in the future using the same preparation method.
LETTER
(11) Tomioka, K.; Kobayashi, Y.; Motohisa, J.; Hara, S.; Fukui, T. Nanotechnology 2009, 20, 145302. (12) Ko, H.; Takei, K.; Kapadia, R.; Chuang, S.; Fang, H.; Leu, P. W.; Ganapathi, K.; Plis, E.; Kim, H. S.; Chen, S.-Y.; Madsen, M.; Ford, A. C.; Chueh, Y.-L.; Krishna, S.; Salahuddin, S.; Javey, A. Nature 2010, 468, 286. (13) Meldrum, A.; Boatner, L. A.; White, C. W. Nucl. Inst. Meth. Phys. Res. B 2001, 178, 7. (14) Komarov, F.; Vlasukova, L.; Wesch, W.; Kamarou, A.; Milchanin, O.; Grachnyi, S.; Mudryi, A.; Ivaniukovich, A. Nuc. Instr. Meth. Phys. Res. B 2008, 266, 3557. (15) Braun, W.; Kaganer, V.; Trampert, A.; Schonherr, H.; Gong, Q.; Notzel, R.; Daweritz, L.; Ploog, K. J. Cryst. Growth 2001, 227, 51. (16) Ladanov, M. Y.; Milekhin, A. G.; Toropov, A. I.; Bakarov, A. K.; Gutakovskii, A. K.; Tenne, D. A.; Schulze, S.; Zahn, D. R. T. J. Exp. Theor. Phys. 2005, 101, 554. (17) Handbook Series on Semiconductor Parameters; Levinstein, M.; Rumyantsev, S.; Shur, M., Eds.; World Scientific: Singapore, 1996; Vol. 2. (18) Baumgart, C.; Helm, M.; Schmidt, H. Phys. Rev. B 2009, 80, 085305. (19) Astromskas, G.; Storm, K.; Karlstr€om, O.; Caroff, P.; Borgstr€om, M.; Wernersson, L.-E. J. Appl. Phys. 2010, 108, 054306. (20) Br€otzmann, M.; Vetter, U.; Hofs€ass, H. J. Appl. Phys. 2009, 106, 063704.
’ AUTHOR INFORMATION Corresponding Author
*E-mail:
[email protected].
’ ACKNOWLEDGMENT Authors thank the Rossendorf Implantation Group for ion implantation and H. Felsmann, G. Schnabel, and I. Skorupa for their careful semiconductor preparation work. ’ REFERENCES (1) Li, Y.; Voskoboynikov, O.; Lee, C. P.; Sze, S. M.; Tretyak, O. J. Appl. Phys. 2001, 90, 6416. (2) Tablero, C. J. Appl. Phys. 2009, 106, 074306. (3) Prucnal, S.; Turek, M.; Drozdziel, A.; Pyszniak, K.; Zhou, S. Q.; Kanjilal, A.; Skorupa, W.; Zuk, J. Appl. Phys. B: Lasers Opt. 2010, 101, 315. (4) Kuo, D. M. T.; Chang, Y. C. Phys. Rev. B 2000, 61, 11051. (5) Heitz, R.; Ledentsov, N. N.; Bimberg, D.; Yu, A.; Egorov, M. V.; Maximo, V. M.; Ustinov, A.; Zhukov, E.; Alferov, Zh. I. Appl. Phys. Lett. 1999, 74, 1701. (6) Mo, Y.-W.; Savage, D. E.; Swartzentruber, B. S.; Lagally, M. G. Phys. Rev. Lett. 1990, 65, 1020. (7) Zhong, Z.; Schwinger, W.; Schaeffler, F.; Bauer, G.; Vastola, G.; Montalenti, F.; Miglio, L. Phys. Rev. Lett. 2007, 98, 176102. (8) Vastola, G.; Marzegalli, A.; Montalenti, F.; Miglio, L. Mater. Sci. Eng., B 2009, 159160, 90. (9) Tanaka, T.; Tomioka, K.; Hara, S.; Motohisa, J.; Sano, E.; Fukui, T. Appl. Phys. Express 2010, 3, 025003. (10) Bj€ork, M. T.; Schmid, H.; Bessire, C. D.; Moselund, K. E.; Ghoneim, H.; Karg, S.; L€ortscher, E.; Riel, H. Appl. Phys. Lett. 2010, 97, 163501. 2818
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