氮化镓材料中深能级中心光离化谱测试与分析

设计了一种可用于测试氮化镓材料深能级中心光离化截面的光谱测试方法,该方法建立在使用PID技术控制氮化镓样品中光电流变化为恒定值的基础上,结合光电流测试、霍尔效应、光强度测试等实验手段给出深能级中心光离化截面的实际值。使用该方法得到的光离化截面测试误差同光电探测器对不同入射光子的响应能力有关,光离化截面测试误差随入射光子能量增加不断增大,在入射光子能量较高的情况下,光离化截面测试误差约为8%。对氮化镓材料深能级中心光离化谱分析发现,即使在入射光子能量小于深能级同导带之间能量差2.85eV的情况下,深能级中心仍能在一定程度上吸收该能量的入射光子,表明深能级中心缺陷同周围晶格产生一定程度的耦合。

Photoionization spectrum measurement and analysis of deep level in GaN epilayers

Photoionization spectrum measurement method was designed based on constant photocurrent control by PID technology. Combined with photocurrent and hall effect measurements, this method can provide exact photoionization cross section in GaN epilayers. The measurement results of GaN epilayers show that, the responsiveness of photoelectric detector is the dominating factor affecting test accuracy. The test error increases with the incident photon energy. An 8% test error can be produced under incident photon with 3.2 eV photon energy. Deep level trap in GaN epilayers can still absorb photons with incident energy less than the energy difference between deep level trap and conductor band (2.85 eV), which implies that the lattice relaxation associated with deep level trap takes places in GaN epilayers.