MOCVD生长的GaN单晶膜的蓝带发光研究

对实验室用ＭＯＣＶＤ方法生长的未掺杂ＧａＮ单晶膜的发光性能进行了研究。结果表明：在室温时未掺杂ＧａＮ单晶出现的能量为２．９ｅＶ左右蓝带发光与被偿度有较强的依赖关系。高补偿ＧａＮ的蓝带发射强，低补偿ＧａＮ的蓝带发射弱。对蓝带发光机理进行了探讨，认为蓝 导带电子过至受主能级的发光（ｅＡ发光）。观察到降低ＧａＮ补偿度能提高ＧａＮ带边发射强度。

Blue Luminescence in Unintentionally Doped GaN Grown by MOCVD

The blue luminescence of unintentionally doped GaN at room temperature was studied. The unintentionally doped GaN films were grown on (0001) oriented Al 2O 3 substrate by MOCVD. TMGa and NH 3 were used for Ga and N sources, respectively. N 2 and H 2 were used as carrier gases. Several analytical techniques were employed to characterize the grown layers. The optical properties of GaN films were measured by photoluminescence (PL), the electrical properties were characterized by the Van der Pauw Hall method at room temperature, and the crystalline quality were analysed by double crystal X ray diffraction (DXRD). The research results indicated that the blue luminescence (about 2 9eV) at room temperature in unintentional doped GaN was obviously related with the compensation ratio. The intensity of blue luminescence was strong in high compensation ratio of GaN, while it was weak in light compensation ratio of GaN. It is considered that the blue luminescence was related with acceptor levels. Further study showed that the peak position of the blue luminescence shifted to lower energy by about 35meV with increasing excitation density, and the peak intensity was superlinear with the excitation density. The blue luminescence in undoped GaN was attributed to the transition from the free electron in conduction band to acceptor levels (eA luminescence).The results indicate that the blue luminescence will be restrained and the band edge emission will increase by using a large flow rate H 2 in the main carrier gas.