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在实验优化MBE工艺条件的基础上,采用蓝宝石(0001)邻晶面衬底制备出了具有较高质量的GaN薄膜.XRD分析表明邻晶面衬底生长的GaN薄膜晶体结构质量明显提高,AFM表征结果显示邻晶面生长的样品表面形貌显著改善.蓝宝石衬底GaN薄膜的瞬态光电导弛豫特性对比实验研究发现,常规衬底生长的GaN薄膜光电导弛豫特性出现双分子复合、单分子复合和弛豫振荡三个过程,持续时间分别为0.91,7.7和35.5ms;蓝宝石邻晶面衬底生长的GaN薄膜光电导弛豫过程主要是双分子复合和单分子复合过程,持续时间分别为0.78和14ms.理论分析表明MBE生长GaN薄膜的持续光电导效应主要起源于本生位错缺陷引发的深能级.
Based on the experimental optimization of the MBE process conditions, a GaN film with high quality was prepared by using sapphire (0001) orthorhombic substrate.The XRD results show that the crystal structure of the GaN thin film grown on the orthorhombic surface is obviously improved, and the AFM The characterization results show that the surface morphology of the orthorhombic growth samples is significantly improved.Compared with the transient photoconductive relaxation behavior of GaN films on sapphire substrates, it is found that the photoconductivity of GaN films grown on conventional substrates appears bimolecular recombination, Monolayer recombination and relaxation oscillation for three durations of 0.91, 7.7 and 35.5 ms, respectively. The photoconductive relaxation process of GaN films grown on the adjacent sapphire substrate is mainly composed of bimolecular and monomolecular recombination. The duration Respectively 0.78 and 14ms.The theoretical analysis shows that the sustained photoconductivity of GaN films grown from MBE mainly originated from the deep level induced by the dislocation defect of the Bunsen.