Hg_(1- x)Cd_x Te禁带宽度附近折射率增强效应

用红外椭圆偏振光谱测量了室温下 Hg1 - x Cdx Te(x=0 .2 76 ,0 .30 9,0 .378)体材料位于禁带宽度之下、附近和之上的折射率 .对每一种组份样品均观察到明显的折射率增强效应 .折射率峰值所对应的能量位置近似等于其禁带宽度 .禁带宽度之上折射率随波长 λ变化可用 Sellmeier色散关系 n2 (λ) =a1 + a2 / λ2 + a3/ λ4+ a4/ λ6进行拟合 .     

红外椭圆偏振光谱研究GaxIn1—xAsySb1—y材料的禁带宽度

采用红外椭辰我谱研究了与ＧａＳｂ衬底近晶格匹配的不同组分ＧａｘＩｎ１－ｘＡｓｙＳｂ１－ｙ样品位于禁带宽度能量位置之上、附近和之下的室温折射率光谱。根据禁带宽度能量位置附近的折射率增强效率确定了ＧａｘＩｎ１－ｘＡｓｙＳｂ１－ｙ样品的禁带宽度,并发现在组分ｘ＝０．２￣０．３之间禁带宽度随组分ｘ近似于线性变化。     

MOCVD—Hg1—xCdxTe／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     

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℃)。     

Hg1—xCdxTe组分与红外透射光谱的关系

根据Hg_(1-x)Cd_xTe吸收系数与光子能量之间的指数关系和文献[3]的实验结果,推导出由透射光谱求组分x的表达式。该式的使用不受测量温度和晶片厚度的限制。实验结果表明,用本文给出的表达式求出的x值与用Finkman法和密度法得到的x值是一致的,但比Finkman法简便。     

GaN外延膜的红外椭偏光谱研究

利用红外椭偏光谱法（IRSE）对生长在蓝宝石衬底上的非故意掺杂的GaN外延膜进行了研究。通过对椭偏光谱的理论计算，拟合了本征GaN中的声子振动参量和等离子振荡的频率及阻尼常量，并由此得到了各向异性的折射率和消光系数的色散曲线以及载流子浓度和迁移率。将得到的电学参数同霍耳测量结果进行了比较。     

氢钝化对Hg1—xCdxTe红外透射谱的影响

采用红外透射测量观测了氢钝化对Ｈｇ１－ｘＣｄｘＴｅ晶片的影响，用分层模型计算了晶片射率，分析了氢钝化增加其透射率，吸收边向短波方向移动，低于禁带宽度能量的吸收降低，透过范围减小的原因。表明氢钝化不仅影响到表面，而且影响到整个体内。原因是经氢钝化处理后杂质或缺陷受到有效钝化，载流子浓度降低，组分Ｘ增加；荷电杂质或缺陷的局域内场影响发失变化；以及荷电杂质或缺陷散射增强。     

Hg1-xCdxTe光导探测器的电学参量分析

测量了Hg     

Hg1-xCdxTe metal-semiconductor-metal (MSM)photodetectors

Metal-semiconductor-metal (MSM) detectors with active layers of Hg _1-xCd_xTe (x=0.62-0.74) and electrode spacings of 2, 4, and 6 μm have been fabricated and characterized. Direct-current measurements have shown a low dark current and high responsivity from 0.15 to 1.5 A/W at 10-V bias. The lowest values of dark current (0.16 mA cm²) were obtained for detectors which incorporated an overlayer of CdTe. For detectors without the overlayer, increasing the Cd mole fraction resulted in a decrease in the dark current and a reduction in the 300-nm responsivity. Measurements of frequency response for these detectors show a maximum loss of 8 dB to 20 GHz. These results compare favorably with high-performance MSM detectors based on In_0.53Ga_0.47As with a lattice-matched barrier layer of In_0.52Al_0.48As     

Temperature dependence of 1/f noise in Hg1-xCdxTe MIS infrared detectors

We measured 1/f noise on Hg_0.71Cd_0.29Te Metal-Insulator-Semiconductor (MIS) infrared detectors operated over the temperature range of 40 K to 90 K under 300 K Infrared (IR) radiation. The purpose of the study was to identify the sources of 1/f noise, especially in relation to the dark current. The devices were operated in the correlated double sampling mode where the voltage across the MIS capacitor was sampled at empty potential well and right after the accumulation of minority carriers in the well due to IR radiation generation. The noise power spectral density for the charge integrated in the MIS well was investigated in relation to the dominant component of dark current. At lower temperatures T⩽65 K, the charge noise power spectral density was found to depend quadratically on the dark current. At higher temperatures, this quadratic dependence did not exist. We attribute the dark current to a mixture of tunneling and depletion-region-originated minority carrier generation which seems to be responsible for 1/f fluctuations in these structures for temperatures below 65 K     

Heterojunction blocking contacts in MOCVD grown Hg1-xCdxTe long wavelength infrared photoconductors

The theoretical and experimental performance of Hg_1-xCd _xTe long wavelength infrared (LWIR) photoconductors fabricated on two-layer heterostructures grown by in situ MOCVD has been studied. It is shown that heterojunction blocking contact (HBC) photoconductors, consisting of wider bandgap Hg_1-xCd_x Te on an LWIR absorbing layer, give improved responsivity, particularly at higher applied bias, when compared with two-layer photoconductors incorporating n⁺/n contacts. An extension to existing device models is presented, which takes into account the recombination rate at the heterointerface and separates it from that occurring at both the contact-metal/semiconductor and passivant/semiconductor interfaces. The model requires a numerical solution to the continuity equation, and allows the device responsivity to be calculated as a function of applied electric field. Model predictions indicate that a change in bandgap across the heterointerface corresponding to a compositional change of Δx⩾0.04 essentially eliminates the onset of responsivity saturation due to minority carrier sweepout at high applied bias. Experimental results are presented for frontside-illuminated n-type Hg_1-xCd_xTe photoconductive detectors with either n⁺/n contacts or heterojunction blocking contacts. The devices are fabricated on a two-layer in situ grown MOCVD Hg_1-xCd_xTe wafer with a capping layer of x=0.31 and an LWIR absorbing layer of x=0.22. The experimental data clearly demonstrates the difficulty of forming n ⁺/n blocking contacts on LWIR material, and indicates that heterojunctions are the only viable technology for forming effective blocking contacts to narrow bandgap semiconductors     

Hg1—xCdxTe光导探测器的电学参量分析

测量了Ｈｇ１－ｘＣｄｘＴｅ光导探测器中电阻率与温度及磁场强度的关系．在Ｓｈｕｂｎｉｋｏｖ－ｄｅＨａａｓ（ＳｄＨ）测量中,发现了表面电子的浓度在１．２～５５Ｋ的范围内没有变化．一个包括体电子和两类表面电子的三带模型被用来分析电阻率随温度变化的关系,由此得到的电学参数与实验及ＳｄＨ测量获得的结果非常符合     

Analysis of Hg1-xCdxSe alloys inelectroreflectance

An electrolyte electroreflectance study on Hg_1-xCd_xSe alloy films is first reported. The critical point energies E₀ and E₁ are obtained for different CdSe composition samples and material homogeneities are also discussed     

The Auger-effect in Hg1−xCdxTe

The temperature dependence of the Auger-lifetime of n-Hg_1−xCd_xTe is investigated both theoretically and experimentally for several values of bandgap and of extrinsic carrier-concentration n_ex in the whole range between room and He-temperatures. For semiconducting compounds a pronounced minimum of the lifetime between 10 and 50K and an exponential increase at still lower temperatures are found. The position of the minimum and the exponent depend mainly on the value of the bandgap and on the ratio of the conduction- and valenceband effective masses. Apart from the extended temperature range, which does not allow the use of classical statistics, our calculation differs from earlier work in so far, as we take the band energies and the overlap integrals of conduction- and valenceband Bloch-functions from a k·p-calculation. For semiconducting compounds, we compare the results with those obtained from an estimate of the overlap integrals given by Antončik and Landsberg. Whereas both results are compatible at high temperatures, characteristic differences occur at low temperatures, where we find the lifetime to be proportional to rather than to n_ex⁻². For semimetallic compounds we calculate a weakly temperature dependent Auger-time of the order of 0.1–1 nsec.     

Hg1?x?y?zCdxMnyZnzTe: A new alternative to Hg1?xCdxTe

The results of studying the most important energy-band parameters of a new quinary semiconductor HgCdMnZnTe solid solution are reported. It is shown that the parameters of HgCdMnZnTe can make this material highly competitive with HgCdTe, which is the main material for infrared photoelectronics in the spectral ranges 3–5 and 8–14 μm. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 38, No. 12, 2004, pp. 1414–1418. Original Russian Text Copyright ? 2004 by Gorbatyuk, Markov, Ostapov, Rarenko.     

Pb1—xGexTe薄膜的光学性质

对PVD沉积Pb1-xGexTe薄膜研究发现Pb1-xGexTe是一种高性能的红外材料,在3－25μm光谱范围具有较好的透光性能,室温下的折射率为4．8－5．6薄膜的光学性质,包括透射率、色散关系以及折射率的温度系数dn/dT,与材料中组分x、环境温度和薄膜的沉积工艺条件有密切关系,适当地改变组分和工艺条件,可以使薄膜的折射率温度系数dn/dT从负变到零并转为正,这对于制备高温度稳定性的红外光学薄膜器件具有重要的意义。     

Hg1-xMnxTe的光学性质研究

根据Hg1-xMnxTe的光学吸收光谱，用Kana模型详细分析了重空穴和导带间的直接跃迁导致的本征光吸收。研究表明当光吸收系数α<103 cm-1时，在导带中没有出现从抛物线色散规律引起的偏离，因而保证了Hg1-xMnxTe带宽的精确确定。