GaN外延材料中持续光电导的光淬灭

Optical Quenching of Persistent Photoconductivity in GaN Epilayer

研究了非故意掺杂和掺Si的n型GaN外延材料持续光电导的光淬灭 .实验发现 ,非故意掺杂GaN的持续光电导淬灭程度远大于掺Si的n型GaN ;撤去淬灭光后前者的持续光电导几乎没有变化 ,后者却明显减小 ;稍后再次加淬灭光 ,前者的持续光电导仍无变化 ,而后者却明显增加 .作者认为两者持续光电导的形成都与空穴陷阱有关 ,用空穴陷阱模型解释了非故意掺杂GaN持续光电导的形成以及淬灭过程 ;掺Si的n型GaN的持续光电导是电子陷阱 (杂质能级 )和空穴陷阱共同作用的结果 ,并且在持续光电导发生的不同阶段其中一种陷阱的作用占主要地位 .

Optical quenching of persistent photoconductivity (PPC) in n-type unintentional doped GaN and Si-doped GaN is investigated.Quenching extent of PPC in the former is much larger than that in the latter.After the quench light PPC is removed nearly no change happens in the former while the PPC decreases obviously in the later.When the quenching light is turned on again after a while,PPC is unchanging in the former while increases instead in the later.The origins of the PPC in unintentional doped and Si-doped GaN both are considered having relations with hole traps based on the experimental results.Hole trap model is used to explain the origin of PPC and its optical quenching in unintentional doped GaN.And the PPC of Si-doped GaN is regarded as the effect of both electron traps and hole traps,one of which is dominant at different stages of PPC.