InAsSb势垒阻挡型红外探测器暗电流特性研究

Research on dark current characteristics of InAsSb Barrier-blocking infrared detector

计算了不同温度下由辐射复合和俄歇复合决定的InAsSb材料的载流子寿命,结果表明,低温下n型InAsSb材料的载流子寿命受限于辐射复合过程,而高温下InAsSb材料的载流子寿命取决于Auger 1复合过程。讨论了势垒阻挡型器件的暗电流解析模型及暗电流抑制机理,通过在nBn吸收层的另一侧增加重掺杂的n型电极层形成nBnn+结构对吸收区内的载流子进行耗尽,吸收区少数载流子浓度降低约两个数量级,从而进一步降低器件暗电流。成功制备了InAsSb-基nBnn+器件,150 K下器件暗电流低至3×10^(-6) A/cm^(2),采用势垒结构器件的暗电流解析模型对150 K下器件的暗电流进行拟合分析,结果表明由于势垒层为p型掺杂,在吸收层形成耗尽区,导致器件中的产生复合电流并没有完全被抑制,工作温度低于180 K,器件暗电流受限于产生复合电流,工作温度高于180 K,器件暗电流受限于扩散电流。

The carrier lifetimes determined by radiative and Auger 1 recombination in InAs_(1-x)Sb_(x) were calculated at different temperatures.For n-type InAsSb material,at low temperatures,the carrier lifetime is limited by the radiative recombination,while at high temperatures,the Auger 1 process is dominant.An analytical model of dark current for barrier blocking detectors was discussed,by adding a heavily doped n-type InAsSb electrode on the other side of the absorb-er layer to form an nBnn^(+) structure to deplete the carriers in absorber,the hole concentration in absorption region was decreased about two orders of magnitude,further reducing the dark current of the devices.InAsSb-based nBnn^(+) barrier devices have been successfully fabricated and characterized.At 150 K,the devices displayed a dark current density as low as 3×10^(-6) A/cm^(2),the dark current density of the detectors was fitted by the nBn-based architecture analytical current model,the experimental results indicated that due to the p-type doping of the barrier layer,a depletion region was formed in the InAsSb absorber region,resulting in incomplete inhibition of G-R current.At temperatures below 180 K,the dark current of the detector is limited by G-R process,at temperatures above 180 K,the dark current of the device is limited by diffusion current.