图形化蓝宝石衬底掺杂渐变GaN肖特基型紫外探测器

Doping Graded GaN-based Schottky-barrier Ultraviolet Photodetectors on Patterned Sapphire Substrates

在图形化蓝宝石衬底掺杂渐变的氮化镓(GaN)外延片上制备了肖特基型紫外探测器。与传统结构器件相比,该器件表现出显著改善的电学和光学特性:(1)室温下,当偏压为-5V时具有极低的暗电流密度~1.3×10-8 A/cm^2;(2)在零偏压情况下,紫外/可见光抑制比为~4.2×10~3,最高的响应度为~0.147A/W,最大外量子效率为~50.7%,甚至在深紫外波段(250~360nm)平均量子效率也大于40%;(3)平均开启和关闭瞬态响应常数分别为115μs和120μs,基本不随偏压变化,且具有很好的热稳定性;(4)零偏压下热噪声限制的极限探测率为~5.5×10^(13)cm·Hz^(1/2)/W。

A GaN-based Schottky-barrier ultraviolet photodetectors（PDs）with graded doping was prepared on patterned sapphire substrates.Compared with the conventional structure devices,the fabricated PDs show significant improvements in both of the electrical and optoelectronic properties：（1）At room temperature,it exhibits a very low dark current density of-1.3×10^-8 A/cm^2 under a bias of-5V;（2）Under zero bias,it has a large ultraviolet/visible rejection ratio of-4.2×10^3,a highest photo-responsivity of-0.147A/W and a maximum external quantum efficiency of-50.7%.Even in deep-UV region（250-360nm）,the average quantum efficiency is still greater than 40%;（3）The average rise and fall time constants are estimated to be-115μs and 120μs respectively,which are almost unchanged with the increasing bias and temperature,showing good thermal stability;（4）The specific detectivity limited by the thermal noise is determined to be-5.5×10^13 cm·Hz^1/2/W at 0V.