Low-temperature synthesis and characterization of GaN nanocrystals from gallium trichloride precursor
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L. Liub) Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, People’s Republic of China
J.K. Liang Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, People’s Republic of China; and International Centre for Materials Physics, Academia Sinica, Shenyang 110016, People’s Republic of China
G.B. Song Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, People’s Republic of China; and College of Material Science and Engineering, Southwest University of Science and Technology, Mianyang, 621002, People’s Republic of China
L.T. Yang, J. Luo, Y.Q. Zhou, H.W. Dong, and G.H. Rao Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, People’s Republic of China (Received 23 February 2004; accepted 8 July 2004)
Gallium nitride (GaN) has been synthesized by reacting gallium trichloride with ammonia (NH3) at low temperatures ranging from 500 to 1000 °C for 12 h. X-ray diffraction, transmission electron microscopy, infrared, and Raman backscattering spectra revealed that the synthesized GaN powder consists of single-phase nano-sized crystallites with the wurtzite-type structure. The average size of the crystals decreases with the reaction temperature from approximately ∼63 nm at 1000 °C to ∼5 nm at 500 °C. GaOCl and ⑀–Ga2O3 are the intermediate products during synthesis of the GaN. Characteristic shifts of the Raman peaks are associated with the change in crystal size. The band-edge emission of GaN at 361 nm was observed on room temperature photoluminescence spectra exclusively for the sample synthesized at 1000 °C, while a new and broad emission band appeared with the center ranging from 827 to 765 nm for the samples synthesized between 500 and 800 °C.
I. INTRODUCTION
Gallium nitride (GaN), which has a band gap of 3.45 eV at room temperature, and its related alloys (e.g., Ga1−xInxN) have been of interest due to their light emission in the blue range of the light spectrum. The extensive investigation of GaN has been fueled by the demand and necessity for short wavelength current-injected laser diodes (LD) and light emitting diodes (LEDs). The band
Address all correspondence to these authors. a) e-mail: [email protected] b) e-mail: [email protected] DOI: 10.1557/JMR.2004.0448 3484
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J. Mater. Res., Vol. 19, No. 12, Dec 2004 Downloaded: 18 Aug 2014
gaps and strong chemical bonding of these III–V materials afford high-temperature (>600 °C) applications such as blue LDs and blue and green LEDs. Other applications include read–write laser sources for high-density information storage magnetic and optical media, laser printers, and full-color electroluminescent displays.1 Various Ga compounds are generally used to grow epitaxial GaN thin films or powder. For example, metalorganic chemical vapor deposition (MOCVD)
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