In源流量与Ⅲ族流量之比对InGaN/GaN多量子阱性质的影响

Effect of the ratio of TMIn flow to group Ⅲ flow on the properties of InGaN/GaN multiple quantum wells

利用x射线三轴晶衍射和光致发光谱研究了生长参数In源流量与Ⅲ族流量之比对InGaN GaN多量子阱结构缺陷 (如位错密度和界面粗糙度 )和光致发光的影响 .通过对 (0 0 0 2 )对称和 (1 0 1 2 )非对称联动扫描的每一个卫星峰的ω扫描 ,分别测量出了多量子阱的螺位错和刃位错平均密度 ,而界面粗糙度则由 (0 0 0 2 )对称衍射的卫星峰半高全宽随级数的变化得出 .试验发现多量子阱中的位错密度特别是刃位错密度和界面粗糙度随In源流量与Ⅲ族源流量比值的增加而增加 ,导致室温下光致发光性质的降低 ,从而也证明了刃位错在InGaN GaN多量子阱中充当非辐射复合中心 .

Triple_axis x_ray diffraction (TXRD) and photoluminescence (PL) spectra are used to assess the influence of the ratio of TMIn flow to group Ⅲ flow on structural defects, such as dislocations and interface roughness, and optical properties of multiple quantum wells(MQWs). In this paper the mean densities of edge and screw dislocations in InGaN/GaN MQWs are obtained by ω scan of every satellite peak of (0002) symmetric and (1012) asymmetric diffractions. At the same time, the interface roughness is measured by the radio of the full width at half maximum of satellite peaks to the peak orders. The experimental results showed that the density of dislocation, especially of edge dislocation, and interface roughness increase with the increase of the ratio, which leads to the decrease of PL properties. It also can be concluded that the edge dislocation acts as nonradiative recombination centers in InGaN/GaN MQWs. Also noticed is that the variation of the ratio has more influence on edge dislocation than on screw dislocation.