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基于X射线衍射和原子力显微分析,研究了MOCVD生长的InGaN合金的表面形貌和光致发光光谱。结果发现本实验所用InGaN合金样品表面形貌呈现类花生状微结构团簇,纳米尺度较小的球状富铟InGaN颗粒附着在较大颗粒上;X射线衍射数据计算得微晶粒度折合当量直径约23nm。原子力显微测量得典型的微结构团簇横向宽度约400nm~900nm,表面粗糙度在所选择的6.43μm区域内方均根值为11.52nm,3.58μm区域内方均根值为8.48nm。在室温下用325nm连续激光激发测得样品的表面发光光谱,结果显示光致发光光谱出现多峰结构,其主要发光峰峰值波长分别位于569nm、532nm和497nm。理论计算分析认为发光光谱多峰结构可能是由于InGaN/GaN异质结构形成的F-P垂直腔中多光束干涉调制效应造成的,同时InGaN合金的尺度和组分涨落导致较宽的发光峰。研究结果对设计GaN基半导体光电子器件具有一定的参考价值。
Based on X-ray diffraction and atomic force microscopy, the surface morphology and photoluminescence spectra of InGaN grown by MOCVD were studied. The results showed that the surface morphology of InGaN alloy used in this experiment showed peanut-like microstructure clusters, and the nanoscale spherical indium-rich InGaN particles were attached to the larger particles. The calculated equivalent crystallite size 23nm. The transverse width of typical microstructure clusters obtained by atomic force microscopy was about 400-900 nm. The surface roughness was 11.52 nm for the selected 6.43 μm area and 8.48 nm for the 3.58 μm area. The surface luminescence spectra of the samples were measured by continuous laser excitation at 325 nm at room temperature. The results showed that the photoluminescence spectra showed a multi-peak structure with the main peak wavelengths at 569 nm, 532 nm and 497 nm, respectively. The theoretical calculation shows that the multi-peak structure of the luminescence spectrum may be caused by the multi-beam interference modulation effect in the F-P vertical cavity formed by the InGaN / GaN heterostructure, while the scale and composition fluctuation of the InGaN alloy lead to a wider luminescence peak. The research results have certain reference value for the design of GaN-based semiconductor optoelectronic devices.