长波碲镉汞材料As掺杂激活研究

利用离子注入工艺实现长波碲镉汞材料的As掺杂,As作为掺杂介质表现出两性掺杂行为,而As只有占据Te位成为受主才能形成P型碲镉汞材料。通过对砷掺杂碲镉汞材料在汞气氛中进行退火,分析注入退火引起的样品电学性质的变化,对砷激活退火采用的汞压、温度及时间进行了研究,利用霍尔测试和二次离子质谱仪(SIMS)等手段分析激活效果,研究发现,高温富汞热退火可以实现碲镉汞As激活。     

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。     

高工作温度p-on-n中波碲镉汞红外焦平面器件研究

As注入掺杂的p-on-n结构碲镉汞红外探测器件具有少子寿命长、暗电流低、R₀A值高等优点,是高温器件研究的重要技术路线之一。针对阵列规模640×512、像元中心距15 μm 的As掺杂工艺制备的p-on-n中波碲镉汞焦平面器件,测试了不同工作温度下的性能和暗电流。研究结果表明,在80 K工作温度下,器件响应表现出高响应均匀性,有效像元率达99.98%;随着工作温度升高,器件盲元增多,当工作温度为150 K和180 K时,有效像元率降低至99.92%和99.32%。由于对器件扩散电流更好的抑制,器件在160~200 K温度范围内的暗电流低于Rule-07。并且当工作温度在150~180 K时（300 K的背景下）,器件具有较好的信噪比,极大程度地体现了高温工作的可行性。     

As掺杂碲镉汞富碲液相外延材料特性的研究

对富碲液相外延As掺杂碲镉汞(HgCdTe)材料的研究发现,其电学性能存在着不稳定性,材料霍尔参数的实验数据与均匀材料的理论计算结果也不能很好的吻合.通过采用剥层变温霍尔测量和二次离子质谱(SIMS)测试对材料纵向均匀性进行检测的结果显示,外延材料中的As在高温富汞激活退火过程中具有向材料表面扩散的效应,导致在表面形成了高于主体层浓度1～2个量级的高浓度表面层,并导致了AsTe受主的浓度在HgCdTe薄膜中呈非均匀分布.考虑这一效应并采用双层模型的霍尔参数计算方法后,As掺杂HgCdTe液相外延材料的电学行为得到了较好的解释,并较为准确地获得了退火后材料表面层与主体层的受主浓度及受主能级等电学参数.     

中波碲镉汞p-on-n高温工作技术研究

针对碲镉汞中波p-on-n技术进行研究,采用二次离子质谱仪分析注入后及退火后As离子在碲镉汞材料中的浓度分布,使用透射电镜表征激活退火后离子注入损伤修复状态,通过半导体参数测试仪评价pn结的IV特性,将探测器芯片装在变温杜瓦中测试其不同温度下的焦平面技术指标。研究结果表明,As离子注入后在碲镉汞体内形成大量缺陷,经过富汞退火后缺陷得到修复,同时As离子进一步向内扩散,制备的pn结工作稳定表明As离子得到有效激活,制备的中波p-on-n探测器芯片在120 K温度下有效像元率可以达到99%以上。     

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As掺杂技术研究

对于MBE原位掺杂,HgCdTe的N型掺杂比较容易,而P型掺杂相对来说难度比较大。作为掺杂杂质的As表现出两性掺杂行为,在富Te的条件下生长,As有很大的几率进入到阳离子位置处。而As必须进入Te位才能参与导电,表现为P型。因此,采取了多种方法,现已获得10^16-10^18坤cm^-3掺杂水平的P型材料。在成功实现As的掺杂后,研究人员对激活退火做了一些研究。研究发现,需要在汞压下经过高温退火,As原子才能占据Te位成为受主杂质。对As在碲镉汞中的扩散系数也进行了研究。     

低暗电流高温工作碲镉汞红外探测器制备技术

报道了与传统的n-on-p结构相比具有更低暗电流的p+-on-n型碲镉汞红外探测器的研究进展。通过水平滑舟富碲液相外延生长的方法在碲锌镉衬底上原位生长In掺杂碲镉汞n型吸收层材料,然后再分别采用As离子注入技术和富汞垂直液相外延技生长技术实现了P型As外掺杂的p+-on-n型平面型和双层异质结台面型两种结构的芯片制备。碲镉汞探测器的主要缺点是需要低温制冷,期望碲镉汞探测器在不降低性能的前提下具有更高的工作温度(High Operating Temperature,HOT),成为红外探测器技术发展的主要方向。本文对基于标准的n-on-p(Hg空位)掺杂工艺及新研制的p-on-n型As离子注入及异质结制备技术的探测器进行了高温性能测试,测试结果表明采用p-on-n型的碲镉汞探测器能够实现更高的工作温度。     

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”;     

长波碲镉汞材料的低温退火

本文分析和讨论了碲镉汞材料退火的微观机制和退火条件，根据分析的结果对加速旋转坩埚技术布里奇曼法生长的长波碲镉汞材料进行了低温退火实验，取得了满意的结果。对于０．７ｍｍ厚的样品，１９０～２２０℃下汞饱和等温退火５０～６０天可获得电学性能优良的ｎ型材料。７７Ｋ下载流子浓度ｎ＜５×１０１４ｃｍ－３，载流子迁移率μ＞１×１０５ｃｍ２／Ｖ·Ｓ，少子寿命τ＞１μｓ。     

As离子注入碲镉汞的p+n结红外探测器

讨论了制作pn结的另一种途径,即在n型HgCdTe材料上离子注入As+,然后通过辐射快速退火形成反型p+层来获得p+n结.通过对制作工艺及实验结果的讨论,阐述了两种制作pn结工艺的特点.实验表明,采用辐射快速退火工艺可以在短时间内完成对HgCdTe注入表面的缺陷退火和杂质激活,而不会改变HgCdTe 组份.已用此方法在注入As+的n型HgCdTe样片上制作出性能较好的p+n结光伏红外探测器.     

MCT液相外延薄膜的生长和特性

用开管水平液相外延系统从富Te溶剂中生长了不同x值的MCT薄膜。经X射线衍射、Hall电学参数、红外光谱、扫描电镜、X射线能谱仪和电子通道花样分析测试,结果表明:外延薄膜表面平整,光学参数较好,纵向、横向组份均匀,晶体结构完整,电学参数较好,外延膜质量优良。短波材料(n型):载流子浓度3.54×10~(14)cm~(-3),迁移率1.63×10~4cm~2V~(-1)s~(-1);中波材料(n型):载流子浓度9.95×10~(14)cm~(-3),迁移率为1.76×10~4cm~2V~(-1)s~(-1);原生长波材料(n型):载流子浓度为2.15×10~(15)cm~(-3),迁移率2.00×10~4cm~2V~(-1)s~(-1)。     

Molecular beam epitaxy growth of high-quality arsenic-doped HgCdTe

We have initiated a joint effort to better elucidate the fundamental mechanisms underlying As-doping in molecular beam epitaxy (MBE)-grown HgCdTe. We have greatly increased the As incorporation rate by using an As cracker cell. With a cracker temperature of 700°C, As incorporation as high as 4×10²⁰ cm⁻³ has been achieved by using an As-reservoir temperature of only 175°C. This allows the growth of highly doped layers with high quality as measured by low dislocation density. Annealing experiments show higher As-activation efficiency with higher anneal temperatures for longer time and higher Hg overpressures. Data are presented for layers with a wide range of doping levels and for layer composition from 0.2 to 0.6.     

MCT液相外延薄膜的研制

用开管水平卧式液相外延系统在不同生长条件下生长了不同 x 值的MCT 液相外延薄膜。通过对外延生长工艺的控制,外延薄膜的表面形貌有较大改善,残留母液大为减少;外延薄膜的结构参数、电学参数和光学参数均有较大改善和提高。分析表明外延膜有较高的质量。短波材料和中波材料均已作出性能较高的器件。     

Halogen lamp rapid thermal annealing of Si- and Be-implanted In0.53Ga0.47As

Halogen lamp rapid thermal annealing was used to activate 100 keV Si and 50 keV Be implants in In_0.53Ga_0.47As for doses ranging between 5 × 10¹²−4 × 10¹⁴ cm⁻². Anneals were performed at different temperatures and time durations. Close to one hundred percent activation was obtained for the 4.1 × 10¹³ cm⁻² Si-implant, using an 850° C/5 s anneal. Si in-diffusion was not observed for the rapid thermal annealing temperatures and times used in this study. For the 5 × 10¹³ cm⁻² Be-implant, a maximum activation of 56% was measured. Be-implant depth profiles matched closely with gaussian profiles predicted by LSS theory for the 800° C/5 s anneals. Peak carrier concentrations of 1.7 × 10¹⁹ and 4 × 10¹⁸ cm⁻³ were achieved for the 4 × 10¹⁴ cm⁻² Si and Be implants, respectively. For comparison, furnace anneals were also performed for all doses.     

Beryllium Ion Implantation into GaAs and Pseudomorphic AIGaAs/lnGaAs/GaAs Heterostructure

Implantations of Be, Be + P, Be + F, Be + P +F, BeF and Mg + P into GaAs and AlGaAs/InGaAs/GaAs pseudomorphic heterostructure were evaluated by secondary ion mass spectrometry profilings and electrical resistivity measurements. Rapid thermal annealing causes a strong diffusion of Be when implanted alone. Co-implantation with P prevents both diffusion and degradation of the Gaussian-shape implant distribution and thus improves the semiconductor sheet resistivity. Annealing at 850°C for 10 s for a Be + P co-implant results in a 60% activation efficiency, and lower diffusion and resistivity when compared to single Be, Be + F, Be + F + P, BeF, and Mg + P implanted at the same dose.     

Effect of Chemical Doping and Ion Implantation on Conductivity of Poly （p-phenylene vinylene） Derivatives

The surface conductivity of poly [2-methoxy-5-(3 '-methyl)butoxy]-p-phenylene vinylene (PMOMBOPV) films doped with FeCl3 and H2 SO4 by chemical method and implanted by N ions was studied and the comparison of environmental stability of conductive behavior was also investigated. The energy and dose of N ions were in the rang 15～35 kev and 3. 8× 1015 ～9. 6× 1016 ions/cm2, respectively. The conductivity of PMOMBOPV film was enhanced remarkably with the increases of the energy and dose of N ions. For example, the conductivity of PMOMBOPV film was 3.2 × 10-2 S/cm when ion implantation was performed with an energy of 35 kev at a dose of 9. 6 × 1016 ions/cm2 , which was almost seven orders of magnitude higher than that of film unimplanted. The environmental stability of conductive behavior for ionimplanted film was much better than that of chemical doped films. Moreover, the conductive activation energy of ion-implanted films was measured to be about 0.17 eV.     

From Long Infrared to Very Long Infrared Wavelength Focal Plane Arrays Made with HgCdTe n + n ?/ p Ion Implantation Technology

This paper aims at studying the feasibility of very long infrared wavelength (VLWIR) (12–18 μm) focal plane arrays using n-on-p planar ion-implanted technology. To explore and analyze the feasibility of such VLWIR detectors, a set of four Cd _x Hg_1−x Te LPE layers with an 18 μ cutoff at 50 K has been processed at Defir (LETI/LIR–Sofradir joint laboratory), using both our “standard” n-on-p process and our improved low dark current process. Several 320 × 256 arrays, 30-μm pitch, have been hybridized on standard Sofradir readout circuits and tested. Small dimension test arrays characterization is also presented. Measured photonic currents with a 20°C black body suggest an internal quantum efficiency above 50%. Typical I(V) curves and thermal evolution of the saturation current are discussed, showing that standard photodiodes remain diffusion limited at low biases for temperatures down to 30 K. Moreover, the dark current gain brought by the improved process is clearly visible for temperatures higher than 40 K. Noise measurements are also discussed showing that a very large majority of detectors appeared background limited under usual illumination and biases. In our opinion, such results demonstrate the feasibility of high-performance complex focal plane arrays in the VLWIR range at medium term.     

Improved Defect and Fourier Transform Infrared Spectroscopy Analysis for Prediction of Yield for HgCdTe Multilayer Heterostructures

The ability to accurately predict HgCdTe focal plane array (FPA) performance using nondestructive, postgrowth wafer analysis is of great importance. These predictions, if accurate, reduce costs by screening the wafers prior to processing, and selecting only those wafers that are most likely to yield FPAs that meet program specifications. In this paper, we examine the use of a macrodefect inspection tool, the NSX 1255, from August Technology. This inspection tool has the ability to measure defects 0.5 μm and larger and store the location and size data to a file. We have then, through the use of custom written software, been able to analyze these data on a wafer by wafer basis. We have also incorporated the use of a thin film transmission matrix model to analyze room-temperature Fourier transform infrared spectroscopy (FTIR) transmission spectra. This technique, which is applied to the entire wafer surface, can be used to determine the individual layer thicknesses as well as their compositions. Then, using analytical expressions for bandgap, absorption, and index of refraction, we can predict responsivity and quantum efficiency. Through the use of these two inspection tools and our analysis software, we are able to overlay FPA die information and perform statistics on a die-per-die basis. This allows us to effectively “pass” or “fail” each FPA based on the program specifications. We are then able to set a minimum criterion for the number of FPAs that pass on any given wafer. That wafer is then sent off to processing if it meets this criterion. Furthermore, knowing why a wafer fails before it reaches processing allows for real time feedback to the epilayer growth process. This allows for run-to-run adjustments in order to keep as many wafers within specifications as possible and increases yield overall. (Received October 24, 2006; accepted Feburary 26, 2007)