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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.
The p + -on-n heterojunction material prepared by As doping and activation technology is one of the key technologies for obtaining high-performance long-wave HgCdTe infrared focal plane devices, and has drawn wide attention. Using variable temperature IV fitting method, The relationship between the different As doping concentration and the device junction performance was analyzed and it was found that decreasing the As doping concentration in the junction region can effectively restrain the trap-assisted tunneling current of the device. The fitting results indicate that the higher concentration of Nt is likely to be associated with high concentration As doping, it is considered that the stable uniform incorporation and activation of As are the main technical challenges.The relationship between the Hg / Te beam current ratio and the As doping efficiency in molecular beam epitaxy was experimentally studied, and it was found that the relative Hg-rich epitaxial condition It is also found that the doping uniformity of As in the wafer is closely related to the homogeneity of the Hg / Te beam current ratio.The activation annealing of As is studied and found that in the saturated Hg vapor pressure The as atom activation rate in HgCdTe can be significantly improved by the annealing conditions of 300 ℃ / 16h + 420 ℃ / 1 h + 240 ℃ / 48 h.