不同钝化结构对非极性AlGaN-MSM紫外探测器性能的提升

Performance Enhancement of Nonpolar AlGaN-MSM Ultraviolet Photodetetors by Different Passivation Layers

在r面蓝宝石衬底上,采用金属有机化学气相沉积(MOCVD)法高温生长了未掺杂非极性AlGaN半导体薄膜,在此基础上制备了金属-半导体-金属(MSM)结构的紫外探测器。系统研究了在AlGaN半导体薄膜表面分别磁控溅射SiO_2纳米颗粒与SiO_2钝化层两种钝化手段对非极性AlGaN-MSM结构的紫外探测器性能的影响。实验结果表明:磁控溅射SiO_2纳米颗粒钝化或SiO_2钝化层两种手段都能提升AlGaN-MSM结构紫外探测器性能。暗电流测试表明,SiO_2纳米颗粒和SiO_2钝化层可使器件暗电流下降1~2个数量级,达到n A量级。光谱响应测试发现,在5 V偏压下,探测器在300 nm处具有陡峭的截止边,这表明其具有很好的深紫外特性,光谱响应提高了103倍,紫外可见抑制比高达105。

The metal-semiconductor-metal（MSM） structure ultraviolet（UV） photodetector was fabricated on the nonpolar AlGaN grown on r -sapphire substrates by metalorganic chemical vapor deposition（MOCVD） using high temperature treatments. The effects of passivation layers by adding SiO 2 nanoparticles（SiO 2-NPs） or SiO 2 layers （SiO 2-Ls） on optical and electrical properties of the nonpolar AlGaN-MSM UV photodetector were investigated systematically. The results indicate that the surface passivation of SiO 2 is an important way to enhance the UV performance of the nonpolar AlGaN-MSM UV photodetector. The fabricated devices are characterized by measurements of the dark I-V characteristic and the spectral response. It was found that the dark current of the AlGaN-MSM UV photodetector decreased by 1-2 orders of magnitude by SiO 2-NPs or by SiO 2-L, which can lower to the order of nA. The detector exhibits a sharp cut-off wavelength at about 300 nm, the spectral response is improved 10 3 times and the ratio of UV to visible reaches as high as 10 5.