大面阵碲镉汞长波红外焦平面器件刻蚀工艺非均匀性研究

作为探测器组件的性能指标之一,响应率非均匀性对其实际应用具有重要影响,尤其是在低背景空间应用领域。大面阵探测器芯片的接触孔尺寸不均匀是导致器件响应不均匀的因素之一。对1280×1024大面阵长波红外探测器芯片的接触孔刻蚀工艺进行了研究,并提出了优化改进措施。结果表明,本文方法可提高刻蚀工艺的均匀性,进而降低探测器组件响应率的非均匀性。     

长波p-on-n碲镉汞红外焦平面器件研究进展

与n-on-p材料相比,p-on-n材料具有更低的暗电流和更高的工作温度,更适于长波以及高温工作碲镉汞红外焦平面器件。介绍了法国Sofradir公司、美国Raytheon Vision Systems公司以及国内的华北光电技术研究所和昆明物理研究所在长波p-on-n器件上的研究进展。     

碲镉汞长波探测器暗电流仿真分析

针对n-on-p型长波Hg1-xCdxTe红外探测器的暗电流进行建模分析,分析了不同机制对暗电流的影响,仿真分析结果和实际结果能够较好地匹配。得出探测器的工作状态暗电流Idark＝9×10-10 A,工作电阻Rr＝109?,品质因子R0A＝20?cm2。从仿真分析结果得出,在现有工艺下,Shockley-Read-Hall （SRH）复合和表面漏电是影响暗电流的最主要的非本征因素,其中SRH复合速率为2×1016/s?cm3,当表面态到达1×1012 cm-2,器件会出现严重的表面沟道。     

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。     

碲镉汞长波探测器暗电流优化模拟

报道了利用Silvaco软件对Hg1-x Cd x Te(x=0.22)n-on-p型长波探测器的模拟仿真结果。采用二维简化pn结模型,以品质因子R0A为标准,模拟计算了载流子寿命、缺陷密度、表面态、p区受主浓度、p区厚度、n区厚度宽度对暗电流的影响,得出在良好的品质因子范围内各个参量可以接受的范围。并针对重要参量利用软件对其复合速率,电流分布,载流子浓度等进行了详细模拟分析,为探测器设计制备提供了参考。     

器件工艺对碲镉汞位错的影响

用化学腐蚀法观察到，器件工艺过程中的机械应力和效应力使碲镉汞（ＨｇＣｄＴｅ）晶片的位错大幅度增殖，汞气氛下低温热处理（２２０℃）使（ＨｇＣｄＴｅ）体材料的位错密度增殖３～４倍，并分别对实验室结果进行了分析讨论．     

长波红外碲镉汞探测器

1 引言 红外辐射最早是1800年英国的天文学家赫谢耳(W.Herschel)在研究太阳光谱的热效应时,用水银温度计测量各种颜色光的加热效果而发现的。1830年,L.Nobili利用塞贝克发现的温差电效应制成了“温差电型辐射探测器”;     

背景辐射对甚长波碲镉汞光导器件性能的影响

通过对甚长波碲镉汞器件的信号、噪声、有效寿命等的测试分析,研究背景辐射对甚长波器件性能的影响.利用冷光阑和黑体照射改变器件接收的背景辐射,设计并搭建了变背景有效寿命测试装置.改变背景辐射,测试甚长波器件的电阻、信号、噪声、噪声频谱、有效寿命.测量结果表明,增加立体角为30°的冷光阑后,随着背景辐射的减小,器件的电阻、信号、噪声、探测率等都有不同程度的增加;噪声频谱测试证明,1 kHz频率处的噪声主要是产生-复合噪声;改变黑体温度的变背景的有效寿命测试结果证明,背景辐射对寿命的影响很大,背景辐射减小,光生载流子的有效寿命增加.分析甚长波器件表面和体内的S-R复合、俄歇复合、辐射复合等复合机制,利用非平衡载流子和器件有效寿命理论对器件的寿命和产生复合噪声随背景辐射的变化进行理论计算,计算结果与实验结果存在一定的差异,但在随背景辐射变化的趋势上一致,并对两者的差别进行了分析.     

长波光导60元碲镉汞红外探测器通用组件

报道了工程化长波光导６０无碲镉汞红外探测器组件研制的结果，该组件由探测器芯片、杜瓦和制冷器组成。探测器组件的主要指标达到：ＤＢ＝１．７×１Ｏ１０ＣｍＨｚ１／２／ＷＶＢ＝１６×１０４Ｖ／Ｗ。组件的体积小，重量轻，并达到了国军标所规定的红外探测器高、低温实验，温度循环实验，振动实验和冲击等环境实验的要求。     

Bake stability of long-wavelength infrared HgCdTe photodiodes

The bake stability was examined for HgCdTe wafers and photodiodes with CdTe surface passivation deposited by thermal evaporation. Electrical and electrooptical measurements were performed on various long-wavelength infrared HgCdTe photodiodes prior to and after a ten-day vacuum bakeout at 80°C, similar to conditions used for preparation of tactical dewar assemblies. It was found that the bakeout process generated additional defects at the CdTe/ HgCdTe interface and degraded photodiode parameters such as zero bias impedance, dark current, and photocurrent. Annealing at 220°C under a Hg vapor pressure following the CdTe deposition suppressed the interface defect generation process during bakeout and stabilized HgCdTe photodiode performance.     

砷掺HgCdTe长波红外光电二极管阵列的制备与性能

采用砷(As)掺杂HgCdTe材料研制了响应截止波长为12.5 μm,规格为256×1的长波红外光电二极管阵列.实验设计了一种新的pn结测量方法,测量发现砷掺长波HgCdTe材料离子注入形成pn结深度在3.6～5.3 μm之间,而其最大横向尺寸大约是设计尺寸的1.3倍.实验采用一种改进的表面处理工艺制备了砷掺HgCdTe长波红外光电二极管阵列,获得了良好的电学性能,该工艺与常规表面处理工艺相比可以使器件峰值阻抗提高2个量级,而-0.5v偏压下的动态电阻可提高约30倍.研究认为,器件性能提高的原因是由于改进工艺可以有效抑制器件表面漏电流.     

回熔过程对HgCdTe长波红外光伏探测器的I-V性能的影响

对三种不同工艺的HgCdTe长波器件(标准工艺、回熔处理、离子注入后退火)的I-V性能分别进行测试,并通过理论计算与实验数据拟合提取上述器件参数,分析暗电流机制及导致暗电流变化的原因。文章中使用的暗电流机制的模型由扩散电流、产生-复合电流、缺陷辅助隧道电流和直接隧道电流组成。从拟合得到的器件参数中可以发现回熔过程中产生了大量的缺陷,导致缺陷辅助隧道电流、产生复合电流显著增加,器件反偏电阻减小,I-V性能变差。与离子注入后退火器件的性能变化相比,推测导致器件回熔后性能下降的原因是ZnS钝化层受热不稳定。     

Tunneling in long-wavelength infrared HgCdTe photodiodes

We have generalized the existing expression for the trap-assisted tunneling current to include the effect of linearly varying electric field in the depletion region and self-consistently calculated steady-state trap occupation probability. We find that the magnitude and variation of current with voltage depend critically on these improvements.     

HgCdTe long-wavelength infrared photovoltaic detectors fabricated using plasma-induced junction formation technology

A long-wavelength infrared (LWIR) HgCdTe photodiode fabrication process has been developed based on reactive ion etching (RIE) plasma-induced p-to-n type conversion for junction formation. The process has been successfully applied to produce devices using both vacancy-doped and gold-doped liquid phase epitaxy (LPE)-grown p-type HgCdTe material with a cut-off wavelength of 10 μm at 77 K. The fabrication procedure is outlined and results are presented on completed devices that indicate the effect of variations in processing parameters. The fabricated devices have been characterized by measurements of the diode dark I-V characteristic over the temperature range 20–200 K, as well as by spectral responsivity measurements. Analysis of the device I-V data, variable area data, and modeling of diode dark current mechanisms indicates that gold-doped material results in higher performing devices compared to vacancy-doped material. Device performance is found to be strongly affected by trap-assisted tunneling currents and surface leakage currents at zero bias. Nonoptimum surface passivation is likely to be the major factor limiting performance at this early stage of device technology development.     

中长波双色碲镉汞红外探测器器件模拟与分析

利用Crosslight公司的APSYS软件模拟准平面结构中长波双色碲镉汞红外探测器的不同结构的光谱串音。研究表明中波层厚度增加将抑制中波对长波的光谱串音,同时将小幅增大长波对中波的光谱串音;阻挡层组分越大,阻挡层与中波层的导带带阶越大,光生载流子跃迁过带阶势垒的几率减少,使得光谱串音减小;阻挡层厚度越大量子隧穿效应减弱,导致光谱串音减小。通过优化器件结构可使中波对长波的光谱串音以及长波对中波的光谱串音都控制在2.5 %以下。     

High performance SWIR HgCdTe detector arrays

Short wave infrared (SWIR) devices have been fabricated using Rockwell’s double layer planar heterostructure (DLPH) architecture with arsenic-ion implanted junctions. Molecular beam epitaxially grown HgCdTe/CdZnTe multilayer structures allowed the thin, tailored device geometries (typical active layer thickness was ∼3.5 μm and cap layer thickness was ∼0.4 μm) to be grown. A planar-mesa geometry that preserved the passivation advantages of the DLPH structure with enhanced optical collection improved the performance. Test detectors showed Band 7 detectors performing near the radiative limit (∼3-5X below theory). Band 5 detector performance was ∼4-50X lower than radiative limited performance, apparently due to Shockley-Hall-Read recombination. We have fabricated SWIR HgCdTe 256 × 12 × 2 arrays of 45 um × 45 μm detector on 45 μm × 60 μm centers and with cutoff wavelength which allows coverage of the Landsat Band 5 (1.5−1.75 μm) and Landsat Band 7 (2.08−2.35 μm) spectral regions. The hybridizable arrays have four subarrays, each having a different detector architecture. One of the Band 7 hybrids has demonstrated performance approaching the radiative theoretical limit for temperatures from 250 to 295K, consistent with test results. D* performance at 250K of the best subarray was high, with an operability of ∼99% at 10¹² cm Hz^1/2/W at a few mV bias. We have observed 1/f noise below 8E-17 AHz ^1/2 at 1 Hz. Also for Band 7 test structures, Ge thin film diffractive microlenses fabricated directly on the back side of the CdZnTe substrate showed the ability to increase the effective collection area of small (nominally <20 μm μm) planar-mesa diodes to the microlens size of 48 urn. Using microlenses allows array performance to exceed 1-D theory up to a factor of 5.     

碲镉汞红外探测器电极接触研究北大核心CSCD

金属/碲镉汞电极接触是红外焦平面探测器的重要组成部分,对器件的性能与稳定性影响较大。然而在碲镉汞金属化过程中,金属离子能量较高将有可能对碲镉汞表面造成损伤。本文采用了离子束沉积系统生长金属电极,探究了束流、束压以及热处理等条件对碲镉汞红外探测器接触性能的影响。研究表明,碲镉汞在生长电极后表面会受到一定程度的损伤;随着离子能量的升高,对材料表面损伤加剧。在I-V曲线中,电极沉积损伤较大的器件表现出软击穿现象;在热处理后,在一定程度上可以修复电极沉积时能量过大造成的损伤,提高了电极接触性能。     

Thermal cycling-induced changes in excess dark current in very long-wavelength HgCdTe photodiodes at low temperature

We have observed cooldown-to-cooldown changes in the reverse-bias dark current of some very long-wavelength (cutoff >14 μm) HgCdTe P-on-n heterojunction photodiodes operated at very low temperatures (40–45 K). Other photodiodes in the same arrays are stable between cooldowns. The unstable ones have high dark currents, in the tail of the dark current distribution. Current-voltage analysis indicates that the high dark current is caused by trap-assisted tunneling and that the number of traps changes from cooldown to cooldown. Devices with negligible trap-assisted tunneling current, limited by diffusion and band-to-band tunneling currents at reverse bias, are stable between cooldowns. Both types of devices are stable within a given cooldown over periods of at least 24 h.     

Effects of hydrogen on majority carrier transport and minority carrier lifetimes in long-wavelength infrared HgCdTe on Si

We present extended results on the use of a hydrogen plasma to passivate the effects of defects in long-wave ir HgCdTe/Si. Annealed and as-grown epilayers, in situ doped with indium, were exposed to a hydrogen plasma generated in an electron cyclotron resonance (ECR) reactor. Secondary ion mass spectrometry was used to measure the extent of hydrogen incorporation into the epilayers. Hall and photoconductive lifetime measurements were used to assess the efficacy of passivation. The passivation of defects responsible for the scattering and recombination of electrical carriers was observed for most ECR conditions over a range of dislocation densities.