MBE生长碲镉汞的砷掺入与激活

采用As掺杂和激活技术制备的p+-on-n异质结材料是获得高性能长波碲镉汞红外焦平面器件的关键技术之一,得到了广泛关注.采用变温IV拟合的方法,对不同As掺入浓度与器件结性能相关性进行了分析,发现降低结区内As掺杂浓度可以有效抑制器件的陷阱辅助隧穿电流.拟合结果表明,较高浓度的Nt很可能与高浓度As掺入相关.因此As的稳定均匀掺入和激活被认为是主要技术挑战.实验研究了分子束外延过程中Hg/Te束流比与As掺入效率的关系,发现相对富Hg的外延条件有助于提高As掺杂效率.研究还发现As的晶圆内掺杂均匀性与Hg/Te束流比的均匀性密切相关.对As的激活退火进行了研究,发现在饱和Hg蒸汽压中采用300℃/16h+420℃/1 h+240℃/48 h的退火条件能明显提升碲镉汞中As原子的激活率.

Arsenic doping and activations in HgCdTe by MBE

The arsenic doping and activations on HgCdTe (mercury cadmium telluride) p+-on-n heterojunctions grown by MBE (molecular beam epitaxy) have got a lot of attention in fabricating high performance long-wavelength IRFPAs (infrared focal plane arrays). In this paper, the performances of HgCdTe diodes with different arsenic doping concentrations are presented. According to the I-V results and dark current mechanism, the effect of arsenic concentration on the trap-assisted tunneling current was calculated and analyzed. To achieve reproducible doping and activation process, the dependence between arsenic doping efficiency and Hg/Te condition was reported. As activation ratio could be higher than 60% under activated annealing at 300, 420 and 240 degree Celsius under an Hg saturated vapor pressure, which was demonstrated by means of Hall-effect measurements and SIMS (Secondary Ion Mass Spectrometry).