Benzene Thermal Conversion to Nanocrystalline Indium Nitride from Sulfide at Low Temperature Jianping Xiao, Yi Xie,* Rui Tang, and Wei Luo Structure Research Laboratory and Department of Chemistry, UniVersity of Science and Technology of China, Hefei, Anhui 230026, P. R. China Received June 30, 2002 A benzene thermal conversion route has been successfully developed to prepare nanocrystalline indium nitride at 180-200 °C by choosing NaNH 2 and In 2 S 3 as novel nitrogen and indium sources. This route has been also extended to the synthesis of other group III nitrides. The product InN was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and high-resolution TEM, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and infrared spectroscopy (IR). The optical properties of nanocrystalline InN were also recorded by means of UV-vis absorption spectroscopy and photoluminescence (PL) spectroscopy, indicating that the as-prepared sample was within the quantum confinement regime. Finally, the formation mechanism was also investigated. Introduction In the past decades, there has been much interest in the synthesis and characterization of the group III nitrides due to their fundamental physical properties as well as their potential applications as electronic and optoelectronic materi- als in device development. 1 The group III nitrides are ideal for high-power applications and utilization in caustic envi- ronments, because they are chemically inert, are resistant to radiation, and have large avalanche breakdown fields, high thermal conductivities, and large high-field electron drift velocities. 2 The group III nitrides and their alloys have been fabricated into various high-temperature and high-power microelectronic and optoelectronic devices. 2 However, the synthesis of the group III nitrides is especially difficult. Therefore, more and more efforts are made to develop novel synthetic routes of the group III nitrides. Indium nitride, one of the group III nitrides, has currently acquired technological importance for blue/violet light- emitting diodes (LEDs) and laser diodes (LDs). 3 Furthermore, InN has promising transport and optical properties. Its large drift velocity at room temperature can render it better than GaAs and GaN for field effect transistors. 4 A tandem solar cell with an InN cell on the top and a Si cell at the bottom can theoretically achieve a maximum efficiency of 32.1%, 5 which is highly desirable for solar energy applications. However, among the group III nitrides, the growth of InN is the most difficult to achieve because of its low decomposi- tion temperature (427-550 °C), 6 which makes the growth of InN most challenging. The growth of InN is particularly important because it has the lowest energy band gap (1.9 eV for InN, 3.4 eV for GaN, 6.2 eV for AlN 7 ). By alloying InN into either AlN or GaN, the band gap of the semicon- ductor can be lowered into the 2-3 eV range, which is a critical range for making high-efficiency green and yellow visible light sources and detectors. Conventional synthetic methods to semiconductor InN include organometallic precursor routes, 8 pyrolysis of In- (NH 2 ) 3 , 9 high-pressure direct synthesis, 10 atomic layer epi- * E-mail: yxielab@ustc.edu.cn. (1) (a) Morkoc, H.; Mohammad, S. N. Science 1995, 267, 51. (b) Morkoc, H.; Strite, S.; Gao, G. B.; Lin, M. E.; Sverdlov, B.; Burns, M. J. Appl. Phys. 1994, 76, 1363. (c) Matsuoka, T.; Ohki, T.; Ohno, T.; Kawaguchi, Y. J. Cryst. Growth 1994, 138, 727. (2) Neumayer, D. A.; Ekerdt, J. G. Chem. Mater. 1996, 8, 25. (3) (a) Matsuoka, T. AdV. Mater. 1996, 8, 469. (b) Ponce, F. A.; Bour, D. P. Nature 1997, 386, 351. (c) Nakamura, S. Science 1998, 281, 956. (4) O’Leary, S. K.; Foutz, B. E.; Shur, M. S.; Bhapkar, U. V.; Eastman, L. F. J. Appl. Phys. 1998, 83, 826. (5) Yamamoto, A.; Tsujino, M.; Ohkubo, M.; Hashimoto, A. Sol. Energy Mater. Sol. Cells 1994, 35, 53. (6) (a) Jones, A. C.; Whitehouse, C. R.; Roberts, J. S. Chem. Vap. Deposition 1995, 1, 65. (b) Akasaki, I.; Amano, H. J. Cryst. Growth 1995, 146, 455. (7) Strite, S.; Morkoc, H. J. Vac. Sci. Technol. B 1992, 10, 1237. (8) (a) Dingman, S. D.; Rath, N. P.; Markowitz, P. D.; Gibbons, P. C.; Buhro, W. E. Angew. Chem., Int. Ed. Engl. 2000, 39, 1470. (b) Fischer, R. A.; Sussek, H.; Miehr, A.; Pritzkow, H.; Herdtweck, E. J. Organomet. Chem. 1997, 548, 73. (c) Bae, B.; Park, J. E.; Kim, B.; Park, J. T. J. Organomet. Chem. 2000, 616, 128. (d) Fischer, R. A.; Miehr, A.; Metzger, T.; Born, E.; Ambacher, O.; Angerer, H.; Dimitrov, R. Chem. Mater. 1996, 8, 1356. (9) Purdy, A. P. Inorg. Chem. 1994, 33, 282. (10) Bo’ckowski, M. Physica B 1999, 265, 1. Inorg. Chem. 2003, 42, 107-111 10.1021/ic0258330 CCC: $25.00 © 2003 American Chemical Society Inorganic Chemistry, Vol. 42, No. 1, 2003 107 Published on Web 12/06/2002