P型长波Hg1—xCdxTe材料MBE生长技术研究

用分子束外延的方法ＧａＡｓ衬底上研制了Ｐ型长波ＨｇＣｄＴｅ材料，及３２×３２小规模长波混成红外焦平面列阵，其材料的均匀性以及生长材料的参数的可重复性良好，在适当的热处理条件，材料Ｐ型电学参数达到了较高水平，并具有良好的可重复性。     

As掺杂p型碲镉汞材料的研究进展

非本征p 型掺杂碲镉汞材料可以有效克服少子寿命偏低等问题,提高长波和甚长波红外焦平面器件的性能。本文重点阐述了As 掺杂实现p型掺杂的基础性原理,以及在器件方面最新研究进展,为今后As掺杂碲镉汞材料的研究提供依据。     

采用ZnCdTe衬底的MBE Hg1—xCdxTe位错密度研究

报道了用MBE的方法,在ZnCdTe衬底上制备Hg1-xCdxTe薄膜的位错密度的研究结果.研究发现Hg1-xCdxTe材料的位错密度与ZnCdTe衬底的表面晶体损伤、Hg1-xCdxTe生长条件以及材料组分密切相关.通过衬底制备以及生长条件的优化,在ZnCdTe衬底上生长的长波Hg1-xCdxTe材料EPD平均值达到4.2×105cm-2,标准差为3.5×105cm-2,接近ZnCdTe衬底的位错极限.可重复性良好,材料位错合格率为73.7%,可满足高性能Hg1-xCdxTe焦平面探测器对材料位错密度的要求.     

MBE生长HgCdTe材料的As掺杂退火的研究

1 引言 近年来,随着碲镉汞(HgCdTe或MCT)红外焦平面(IRFPA)技术的快速发展,器件对材料的电学性质、面积和均匀性等参数的要求迅速提高。要实现载流子在较大范围内的浓度控制以     

Hg1—xCdxTe重力分离研究

通过实验证实了Hg_(1-x)Cd_xTe熔体中存在HgTe与CdTe之间的重力分离。理论分析表明,Hg_(1-x)Cd_xTe熔体中的HgTe粒子服从玻尔兹曼分布律,HgTe粒子的质量为4.07×10~(-18)g(在835℃)。     

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.     

Process modeling of point defect effects in Hg1-xCdxTe

A model is presented which describes the motion of and interactions among some of the native point defects and foreign impurities in Hg_1-xCd_xTe. Semi-quantitative simulations of typical process problems are performed for cases where only Hg interstitials, Hg vacancies, and cation impurities are important. Results for the formation of n-on-p junctions by the Hg anneal of high vacancy concentration material, indicate that junction depths may be a significant function of the n-type dopant concentration. For the case where low vacancy, n-type material is annealed in a Hg-poor ambient, simulation results confirm the difficulty in forming a high quality, well-defined p-on-n junction. This difficulty arises because of the generation of Hg vacancy/interstitial pairs throughout the bulk during most of the process. It is demonstrated that impurity gettering can be described by our modeling approach. All simulation results attempted to date are consistent with the available experimental data.     

Hg1-xCdxTe光伏探测器的钝化研究

用倒易二维点阵对HgCdTe光伏探测器钝化及其热处理行为进行了研究,发现测射沉积的钝化膜会引起HgCdTe的晶面弯曲,严重的会出现晶面扭曲和mosaic结构,而钝化后的热处理能改善MCT晶体的完整性,在不同的钝化介质层钝化MCT的研究中发现,ZnS钝化层在高温下并不稳定,而CdTe钝化层却能保持较高的耐温性能。     

碲镉汞液相外延薄膜生长技术与性能

用液相外延的方法在ＣｄＺｎＴｅ衬底上生长Ｈｇ１－ｘＣｄｘＴｅ材料,获得了表面形貌好,位错密度低,组份均匀的碲匐汞外延材料,生长工艺对材料的参数控制有较好重复性,外延材料经热处理后,材料的Ｐ型和Ｎ型电学参数都达到较好的水平,并具有良好的可重复性。     

Room temperature characterization of Hg1-xCdxTe P-on-n heterostructure photodiodes

Measurements of 77K R_oA and 300K reverse bias dynamic impedance (R_dA) products at one volt reverse bias has been carried out to assess the degree of correlation of this figure of merit. Planar P-on-n heterostructures were grown on near lattice-matched CdZnTe substrates with Hg_1-xCd_xTe (0.20< x <0.30) by molecular beam epitaxy. These devices were passivated with CdTe and doped with indium and arsenic as n- and p-type dopants, respectively. Current-voltage characteristic of these devices exhibit thermally generated dark currents at small and modest reverse bias. We have observed that R_oA values of these long wavelength infrared P-on-n heterostructure photodiodes at 77K correlate with room temperature R_dA values. Diode arrays with high room temperature R_dA values at one volt reverse bias also have high R_oA values at 77K. Similarly, low R_dA values at room temperature indicate poor performance at 77K where deviation from diffusion current occurs at reverse bias of 0.2 to 1 volt at room temperature. The results presented here, for a small samples of devices, demonstrate that room temperature measurements of current-voltage characteristics to evaluate Hg_1-xCd_xTe (0.22< x <0.28) diode performance and array uniformity at lower temperatures can be used. This provides an acceptable criteria for further study at lower temperatures.     

P型长波Hg_（1－x）Cd_xTe材料MBE生长技术研究

用分子束外延的方法在ＧａＡｓ（２１１）Ｂ衬底上研制了Ｐ型长波ＨｇＣｄＴｅ材料，及３２×３２小规模长波混成红外焦平面列阵，其材料的均匀性以及生长材料的参数的可重复性良好．在适当的热处理条件下，材料Ｐ型电学参数达到了较高水平，并具有良好的可重复性     

Si基复合衬底碲镉汞液相外延技术的研究

文章报道了采用Si基复合衬底,利用液相外延方法成功进行中波碲镉汞薄膜生长的情况,并且采用X光双晶衍射、X光形貌、红外付立叶光谱仪等手段对碲镉汞薄膜进行了表征。Si基复合衬底碲镉汞外延膜晶体结构为单晶,并且它的双晶衍射半峰值接近国外同类产品的先进水平。     

Determination of cut-off wavelength and composition distribution in Hg1-xCdxTe

The determination of cut-off wavelength, λ _co, and composition distribution for Hg_1-xCd_xTe has been discussed in this paper. A shift of the cut-off wavelength was found from the photo-response calculation for the HgCdTe devices with the same energy gap E_g but different thickness d. An expression of λ _co(x,T,d) has been derived from the half-maximum photo-response curve calculation. The composition uniformity has been determined from the room-temperature transmission fitting procedure. The composition real space distribution is suggested to be determined by the combination of absorption edge phenomenon and thermal imaging technique.     

MOCVD－Hg_（1－x）Cd_xTe／CdTe／GaAs外延材料红外吸收光谱研究

从理论上完成对ＭＯＣＶＤ工艺生长的ＨｇＣｄＴｅ／ＣｄＴｅ／ＧａＡｓ材料的透过率、吸收边和相干行为的计算．结果表明光的干涉条纹与外延层ＨｇＣｄＴｅ和缓冲层ＣｄＴｅ的总厚度相关，其透过率不能直接反映材料的内在质量．计算结果还表明，外延材料组份的均匀性对红外光谱的吸收边有很大的影响．运用理论计算对实验中测得的光谱曲线进行了分析，发现ＭＯＣＶＤ工艺存在着一种部分过饱和态的生长机制，并发现负禁带ＨｇＴｅ薄膜也具有一定的透光特性．     

Process modeling and simulation for Hg1-xCdxTe. Part II: Self-diffusion,interdiffusion, and fundamental mechanisms of point-defect interactions in Hg1-xCdxTe

The Hg_0.8Cd_0.2Te type-conversion, Hg self-diffusion and interdiffusion processes are analyzed in the context of a first order reaction kinetics approach. Sets of nonlinear, stiffly coupled continuity equations are presented which describe the underlying physics, and their solutions model the observed macroscopic behavior. It is demonstrated that the Frenkel pair mechanism interactions dominated by the cation sublattice, in conjunction with basic diffusive and drift properties of the ionized point defects, comprise the basic processes which effect all macroscopic phenomena discussed. Existing experimental results are reviewed and apparent discrepancies discussed. Use is made of the Stanford University mercury cadmium telluride process simulator to provide quantitative and insightful examples of important results.