砷注入碲镉汞光电二极管及其电学特性的等效分析

通过对碲镉汞材料进行Ａｓ＾＋注入以及退火，成功地制备Ｐ－ｏｎ－Ｎ型光伏器件。器件的截止波长为５．５μｍ，黑体探测率Ｄ＾＊（５００Ｋ，１Ｋ，１００）可达２．１×１０＾１０ｃｍＨｚ＾１／２Ｗ＾－１。通过对器件的变温电流－电压关系的测量，利用等效电路进行拟合后，我们发现，限制器件优质因子ＲｏＡ的主要因素是并联电阻。估计此并联电阻可能由表面漏电和体缺陷引起。     

中波碲镉汞光电二极管pn结特性研究

采用液相外延(LPE)生长的中波HgCdTe薄膜,基于B离子注入n-on-p平面结技术,制备了LBIC测试结构和I-V测试芯片并进行了相应的测试和分析.LBIC测试结果表明,HgCdTe pn结实际结区尺寸扩展4～5 μm,这主要与光刻、B离子注入以及注入后低温退火等器件工艺有关.二极管器件C-V和I-V特性研究表明,所制备的HgCdTe pn结不是突变结也不是线性缓变结.中波HgCdTe二极管器件最高动态阻抗大于30GΩ,器件优值R0A高达1.21×105Ωcm2,表现出较好的器件性能.     

中波碲镉汞雪崩光电二极管的增益特性

采用不同工艺制备了中波碲镉汞(Hg Cd Te)雪崩二极管(APD)器件,利用不同方法对其结特性和增益随偏压变化关系进行了表征,并基于Beck模型和肖克莱解析式进行了拟合分析.结果表明,不同工艺制备的APD器件饱和耗尽区宽度分别为1. 2μm和2. 5μm,较宽的耗尽层有效抑制了高反偏下器件的隧道电流,器件有效增益则从近100提高至1 000以上.用肖克莱解析式拟合Hg Cd Te APD器件增益-偏压曲线,获得了较好的效果.拟合结果与Sofradir公司的J. Rothman的报道相似.     

掺砷碲镉汞的研究进展

掺砷碲镉汞是一科用于制作p-on-n器件和实现高性能碲镉汞探测器及多色红外焦平面阵列的关键材料。对掺砷碲镉汞的相关文献进行了归纳分析。砷渺活效率与退火条件及砷的浓度直接相关。对于掺砷浓度在10^16-10^18cm-3范围内的碲镉汞,通过300℃／16h和240℃／4sh两步退火可将样品前表面激活为P型材料,但汞空位的浓度相对于背面较高。样品背面靠近衬底处可能存在AsT和AsHg缺陷。     

注入n型碲镉汞单晶中铟的性能特点

近年来,研究各种杂质对碲镉汞单晶电物理性能的影响的兴趣日增。尤其在进行研究过程中已经表明,为了获得电导性,可适当地利用铟或镓这些Ⅲ族元素作为熔合杂质。这些杂质扩散相当快,能取代金属晶格中的汞或镉原子,起到施主中心的作用。本研究表明,在离子熔合和后继热处理相结合的一定条件下,铟也是呈现出受主特性。     

论碲镉汞光电二极管的暗电流

对于工作在1—30岬波段的各种红外光电探测器来说,碲镉汞（Mercury Cadmium Telluride,MCT）已经成为最重要的一种半导体材料。为了获得最优的性能,MCT探测器的暗电流必须降至最小。主要根据近年来的部分英文文献,从基本概念入手,介绍了有关MCT光电二极管暗电流研究的发展情况,并讨论了对于MCT光电二极管暗电流有关问题的理解和体会。     

碲镉汞雪崩光电二极管在激光雷达上的应用

首先简要介绍激光雷达的主要军事应用、激光雷达对接收器的性能需求及激光雷达接收器的现状,综述碲镉汞材料特点、碲镉汞雪崩光电二极管探测器特点,与现有激光雷达接收器相比碲镉汞雪崩光电二极管作为激光雷达接收器的优势及制备技术;综述国外碲镉汞雪崩光电二极管用于激光雷达接收器的发展现状;最后分析我国发展用于激光雷达接收器的碲镉汞雪崩光电二极管可行性。     

碲镉汞pn结制备技术的研究进展

作为一种禁带宽度可调的半导体,碲镉汞(MCT)至今仍是一种最有效的可在较宽波长(1～25μm)范围内工作的红外探测器.由于材料性质敏感,MCT器件的制备一直是一项具有挑战性的工作.有若干种pn结制备方法可用于制备MCT光伏器件.离子注入是最常用的一种,但该方法需要额外的退火处理.一些替代技术,例如离子束研磨或反应离子刻蚀等,近来年引起较多关注.MCT体晶和外延层的导电类型转换是材料生产和器件制备中最重要的工艺之一.通过对近年来部分英语期刊文献的归纳分析,介绍了MCTpn结制备技术的研究进展.     

甚长波碲镉汞探测器的注入区扩散研究

在碲镉汞甚长波320×256探测器上制备了不同注入区光刻尺寸的区域,通过对不同区域的信号及注入光刻尺寸的关系进行分析对比和数据拟合,获得了不同温度下的扩散距离和单位有效光敏面积在单位时间的响应电压,对于碲镉汞甚长波探测器的器件版图设计和性能提升提供了可靠的数据支撑。     

中波碲镉汞雪崩光电二极管(APD)增益特性

采用不同工艺制备了中波碲镉汞雪崩二极管(HgCdTe APD)器件,利用不同方法对其结特性和增益随偏压变化关系进行了表征,并基于Beck模型和肖克莱解析式进行了拟合分析。结果表明,不同工艺制备的APD器件饱和耗尽区宽度分别为1.2μm 和2.5μm,较宽的耗尽层有效抑制了高反偏下器件的隧道电流,器件有效增益则从近100提高至1000以上。采用拟合HgCdTe APD器件增益-偏压曲线获得了较好的效果,且拟合得到的参数与Sofradir的Rothman的结果相似。     

MBE growth and characterization of in situ arsenic doped HgCdTe

We report the results of in situ arsenic doping by molecular beam epitaxy using an elemental arsenic source. Single Hg_1−xCd_xTe layers of x ∼0.3 were grown at a lower growth temperature of 175°C to increase the arsenic incorporation into the layers. Layers grown at 175°C have shown typical etch pit densities of 2E6 with achievable densities as low as 7E4cm⁻². Void defect densities can routinely be achieved at levels below 1000 cm⁻². Double crystal x-ray diffraction rocking curves exhibit typical full width at half-maximum values of 23 arcsec indicating high structural quality. Arsenic incorporation into the HgCdTe layers was confirmed using secondary ion mass spectrometry. Isothermal annealing of HgCdTe:As layers at temperatures of either 436 or 300°C results in activation of the arsenic at concentrations ranging from 2E16 to 2E18 cm⁻³. Theoretical fits to variable temperature Hall measurements indicate that layers are not compensated, with near 100% activation after isothermal anneals at 436 or 300°C. Arsenic activation energies and 77K minority carrier lifetime measurements are consistent with published literature values. SIMS analyses of annealed arsenic doping profiles confirm a low arsenic diffusion coefficient.     

Modeling of arsenic activation in HgCdTe

We present a theoretical examination of the behavior of arsenic atoms in Hg_1−xCd_xTe for x=0.3, focusing on the thermodynamic conditions that most closely mimic molecular beam epitaxial growth and subsequent annealing steps. We show that, for molecular beam epitaxial growth where tellurium-saturated conditions apply, arsenic incorporates onto the cation sublattice and becomes inactive. A significant fraction of these arsenic atoms are bound to mercury vacancies. We also propose a model of the activation, which involves transfer of the arsenic from the cation to the anion sublattice. The model suggests that activation anneals must be done at high enough temperatures to surmount an activation barrier, and that the phase field from tellurium- to mercury-rich conditions should be traversed slowly enough so that the cation vacancies are not filled before the site transfer can be completed.     

离子注入碲镉汞迁移率谱的研究

文章介绍了分别采用厚度较大的样品的较薄的霍耳器件进行了离子注入和迁移率谱的测试。对于离子注入后的样品，迁移率谱给出明显的两个电导率峰，通过分析说明样品经过离子注入产生了高浓度和低迁移率的表面层。迁移率谱是离注入样品的有效的非破坏分析方法之一。     

Device modeling of HgCdTe vertically integrated photodiodes

Simulations of current-voltage characteristics of ion-implanted n-on-p photodiodes have been performed using SemiCad Device. In order to accurately simulate this device structure, several modifications to the simulator were implemented. These include the modified carrier statistics to account for the nonparabolic band structure of HgCdTe, the correct physics parameters for Shockley-Read-Hall, optical, and Auger recombination, and the Burstein-Moss shift for optical absorption important for heavily doped n-type HgCdTe. With these and other improvements, SemiCad Device is calibrated with the measured ideal dark current of an ion implanted diode and is used to simulate a source of non-ideal dark current from surface-charge induced band-to-band tunneling.     

Mode of arsenic incorporation in HgCdTe grown by MBE

The results of arsenic incorporation in HgCdTe layers grown by molecular beam epitaxy (MBE) are reported. Obtained results indicate that arsenic was successfully incorporated as acceptors in MBE-HgCdTe layers after a low temperature anneal. Secondary ion mass spectrometry and Hall effect measurements confirm that arsenic is incorporated with an activation yield of up to 100%. This work confirms that arsenic can be used as an effective dopant of MBE-HgCdTe after a low temperature annealing under Hg-saturated conditions.     

Improved arsenic doping in metalorganic chemical vapor deposition of HgCdTe andin situ growth of high performance long wavelength infrared photodiodes

Controlled and effective p-type doping is a key ingredient forin situ growth of high performance HgCdTe photodiode detectors. In this paper, we present a detailed study of p-type doping with two arsenic precursors in metalorganic chemical vapor deposition (MOCVD) of HgCdTe. Doping results from a new precursortris-dimethylaminoarsenic (DMAAs), are reported and compared to those obtained from tertiarybutylarsine (TBAs). Excellent doping control has been achieved using both precursors in the concentration range of 3 × 1015-5 × 10¹⁷ cm⁻³ which is sufficient for a wide variety of devices. Arsenic incorporation efficiency for the same growth temperature and partial pressure is found to be higher with DMAAs than with TBAs. For doping levels up to 1 × 10₁₇ cm⁻³, the alloy composition is not significantly affected by DMAAs. However, at higher doping levels, an increase in the x-value is observed, possibly as a result of surface adduct formation of DMAAs dissociative products with dimethylcadmium. The activation of the arsenic as acceptors is found to be in the 152–50% range for films grown with DMAAs following a stoichiometric anneal. However, a site transfer anneal increases the acceptor activation to near 100%. Detailed temperature dependent Hall measurements and modeling calculations show that two shallow acceptor levels are involved with ionization energies of 11.9 and 3.2 meV. Overall, the data indicate that DMAAs results in more classically behaved acceptor doping. This is most likely because DMAAs has a more favorable surface dissociation chemistry than TBAs. Long wavelength infrared photodiode arrays were fabricated on P-on-n heterojunctions, grownin situ with iodine doping from ethyl iodide and arsenic from DMAAs on near lattice matched CdZnTe (100) substrates. At 77K, for photodiodes with 10.1 and 11.1 (im cutoff wavelengths, the average (for 100 elements 60 × 60 μm² in size) zero-bias resistance-area product, R₀A are 434 and 130 ohm-cm², respectively. Quantum efficiencies are ≥50% at 77K. These are the highest R₀A data reported for MOCVDin situ grown photodiodes and are comparable to state-of-the-art LPE grown photodiodes processed and tested under identical conditions.     

一种MCT离子注入工艺的模型及其计算机模拟方法

给出了一种简单而有效的碲镉汞(MCT)离子注入工艺模型,研究了应用该模型进行计算机模拟的数值方法,最后讨论了该模型中一些重要参数的确定方法。     

Effect of dislocations on performance of LWIR HgCdTe photodiodes

The epitaxial growth of HgCdTe on alternative substrates has emerged as an enabling technology for the fabrication of large-area infrared (IR) focal plane arrays (FPAs). One key technical issue is high dislocation densities in HgCdTe epilayers grown on alternative substrates. This is particularly important with regards to the growth of HgCdTe on heteroepitaxial Si-based substrates, which have a higher dislocation density than the bulk CdZnTe substrates typically used for epitaxial HgCdTe material growth. In the paper a simple model of dislocations as cylindrical regions confined by surfaces with definite surface recombination is proposed. Both radius of dislocations and its surface recombination velocity are determined by comparison of theoretical predictions with carrier lifetime experimental data described by other authors. It is observed that the carrier lifetime depends strongly on recombination velocity; whereas the dependence of the carrier lifetime on dislocation core radius is weaker. The minority carrier lifetime is approximately inversely proportional to the dislocation density for densities higher than 10⁵ cm⁻². Below this value, the minority carrier lifetime does not change with dislocation density. The influence of dislocation density on the R₀A product of long wavelength infrared (LWIR) HgCdTe photodiodes is also discussed. It is also shown that parameters of dislocations have a strong effect on the R₀A product at temperature around 77 K in the range of dislocation density above 10⁶ cm⁻². The quantum efficiency is not a strong function of dislocation density.     

γ射线辐照对中波HgCdTe光导器件性能的影响

对中波ＨｇＣｄＴｅ光电导器件用不同剂量的γ射线进行辐照，测量了其辐照前后的响应光谱、体电阻和响应率、探测率的变化，实验发现γ辐照使其峰值波长和截止波长向短波方向稍许移动；器件体电阻上升；而其响应率和探测率都有不同程度的改善。