Department of Materials Science and Engineering (MSE), Pohang University of Science and Technology (POSTECH), Pohang 790-784, Republic of Korea.
Ultramicroscopy. 2013 Apr;127:114-8. doi: 10.1016/j.ultramic.2012.07.009. Epub 2012 Jul 27.
The effects of growth pressure in metal-organic chemical vapor deposition (MOCVD) on the structural and optical properties of InGaN/GaN multiple-quantum-wells (MQWs) grown on c-plane sapphire substrate were investigated by scanning transmission electron microscopy (STEM), atom probe tomography (APT), Raman spectroscopy and electroluminescence (EL) spectroscopy. As the growth pressure decreased, the growth rate of the InGaN layer increased, leading to a decrease in the frequency of the GaN A1(LO) mode peak and broadening of its full width half maximum (FWHM). The intensity of the EL spectra peaked at a growth pressure of 250 Torr with a narrow FWHM at high forward current. These optical properties are explained by either a high degree of compositional fluctuation of indium in the MQW and/or the high crystallinity of the InGaN layer due to the low growth rate under high pressure.
采用扫描透射电子显微镜（STEM）、原子探针层析术（APT）、拉曼光谱和电致发光（EL）光谱研究了金属有机化学气相沉积（MOCVD）中生长压力对 c 面蓝宝石衬底上生长的 InGaN/GaN 多量子阱（MQW）结构和光学性能的影响。随着生长压力的降低，InGaN 层的生长速率增加，导致 GaN A1(LO)模式峰值的频率降低，半峰全宽（FWHM）变宽。在 250 托的生长压力下，EL 光谱的强度达到峰值，在高正向电流下具有较窄的 FWHM。这些光学性能可以用 MQW 中铟的组成波动程度较高或由于高压下的低生长速率导致 InGaN 层的结晶度较高来解释。
