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系统研究了掺Si的n型GaN的表面形貌、电学性质和光学性质.GaN薄膜采用金属有机化学气相沉积系统(MOCVD)制备,通过选择不同掺杂流量的SiH4,使n型载流子浓度变化范围为3×1016~5.4×1018cm-3.原子力显微镜研究发现随掺杂浓度的增加样品表面形貌变粗糙,表面位错坑密度增加,表明了晶体质量下降.变温霍尔效应获得载流子浓度随温度的变化曲线(n~1/T),拟合得到不同Si掺杂量下,Si杂质在GaN中的电离激活能在12~22meV之间变化,它是施主波函数的相互作用增强所造成.通过研究迁移率随温度(μ~T)的关系曲线,认为载流子输运过程受不同温度下的散射机制影响.光致发光谱研究了室温下GaN薄膜带边发光和黄带,发现带边发光峰的移动是伯斯坦-莫斯效应和能带重整化效应共同作用的结果,并拟合得到了能带收缩效应系数-1.07×10-8eV/cm,指出黄带的产生和变化与不同Si掺杂浓度下Ga空位的浓度相关.
The surface morphology, electrical properties and optical properties of Si-doped n-type GaN were investigated systematically.The GaN films were prepared by metal organic chemical vapor deposition (MOCVD). By choosing SiH4 with different doping flux, the n-type carrier concentration The range of variation is 3 × 1016 ~ 5.4 × 1018cm-3. The atomic force microscopy shows that with the increase of the doping concentration, the surface morphology of the sample becomes rough and the density of surface dislocation pit increases, indicating that the crystal quality decreases. (N ~ 1 / T), the ionization activation energies of Si impurities in GaN varied from 12 to 22 meV at different Si doping levels, which is the interaction of the donor wave function Enhanced by the mobility of the carrier through the study of the relationship between the temperature (μ ~ T) curve, that the carrier transport process is affected by the scattering mechanism at different temperatures. Photoluminescence spectra at room temperature GaN film edge light and yellow The results show that the shift of the band edge emission is the result of the combination of the Bernstein-Moss effect and the band renormalization effect, and the band contraction effect coefficient of -1.07 × 10 -8 eV / cm is obtained. The yellow band The generation and variation of Ga vacancy with different Si doping concentrations Concentration.