器件参数对GaN基n^+-GaN/i-Al_x Ga_(1-x)N/n^+-GaN结构紫外和红外双色探测器中紫外响应的影响

Effects of AlGaN layer parameter on ultraviolet response of n^+-GaN/i-Al_x Ga_(1-x)N/n^+-GaN structure ultraviolet-infrared photodetector

研究了AlGaN层参数对GaN基n+-GaN/i-AlxGa1-xN/n+-GaN结构紫外和红外双色探测器中紫外响应的影响规律及物理机制.模拟计算发现:降低AlGaN层本底载流子浓度会增加器件的量子效率,当本底载流子浓度不能进一步降低时,可以通过减小AlGaN层的厚度以保证器件的量子效率.在材料生长和器件工艺过程中都应减少界面态.外加较小的反向偏压能大幅度提高紫外量子效率,分析表明,GaN/AlGaN/GaN形成的两个背靠背、方向相反的异质结电场是出现这些现象的根本原因.在实际器件设计中,应该根据需要调节各结构参数,以保证器件的量子效率.

We have investigated the effect of AlGaN layer parameter on the ultraviolet response of n ^＋-GaN /i-AlxGa1-x N /n^ ＋-GaN structure ultraviolet-infrared photodetector and its physical mechanism.Through the simulation,it is found that the decrease of AlGaN background concentration has a positive effect on device＇s ultraviolet quantum efficiency.When AlGaN layer background concentration cannot be reduced,the decrease of its thickness can ensure the efficiency.Besides,interfical state should be minimized during materials growth and device fabrication.In addition,small reverse bias voltage can greatly increase ultraviolet quantum efficiency.All these phenomena may be mainly attributed to the existence of the back-to-back heterojunction and the opposite electrical field.It is suggested that we need to adjust structural parameters to obtain high quantum efficiency according to the materials quality in device design.