In_xGa_(1-x)N薄膜的弯曲因子及斯托克斯移动研究

The Bowing Parameters and Stokes' Shift in InGaN Films

采用常压金属有机化学汽相沉积 (MOCVD)技术以Al2 O3 为衬底在GaN膜上生长了InxGa1-xN薄膜。以卢瑟福背散射 /沟道技术、光透射谱、光致发光光谱对InxGa1-xN/GaN/Al2 O3 样品进行了测试。研究了InxGa1-xN薄膜的弯曲因子及斯托克斯移动。结果表明 ,采用光透射谱、光致发光光谱得到的InxGa1-xN薄膜的禁带宽度一致 ,InxGa1-xN薄膜并不存在斯托克斯移动。InxGa1-xN薄膜的In组分分别为 0 .0 4 ,0 .0 6 ,0 .2 4 ,0 .2 6时 ,其弯曲因子分别为 3.4 0 ,2 .36 ,1.82 ,3.70。随In组分变化 ,InxGa1-xN薄膜的弯曲因子的变化并没有一定的规律 ,表明InxGa1-xN薄膜的禁带宽度随In组分的变化关系复杂。

The In xGa 1-x N/GaN films were grown on (0001) sapphire substrates by metal organic chemical vapor deposit (MOCVD) using a homemade vertical reactor at atmospheric pressure. The properties of In xGa 1-x N layers, such as their chemical component, thickness, the crystalline quality, and optical properties, were investigated by Rutherford backscattering/channeling measurement, transmission measurement and photoluminescence. The bowing parameters and the Stokes' shift in In xGa 1-x N layers were studied. The band gaps of In xGa 1-x N films determined by transmission measurement and photoluminescence are consistent. It indicates that there is no Stokes' shift in In xGa 1-x N layers. When the In contents of In xGa 1-x N layers determined by Rutherford backscattering/channeling measurement are 0.04, 0.06, 0.24 and 0.26, the bowing parameters are 3.40, 2.36, 1.82, 3.70, respectively. The bowing parameters of In xGa 1-x N layers randomly vary. This indicates that the relationship between the band gap of In xGa 1-x N layers and In content is complex and it is hardly to obtain the In content of In xGa 1-x N layers from the transmission or photoluminescence measurement. The phase separation for In xGa 1-x N layers is observed through transmission and photoluminescence measurement.