碲锌镉衬底上中长双色红外碲镉汞分子束外延生长研究

报道了使用分子束外延(Molecular beam epitaxy,MBE)技术,在(211)B碲镉汞(CdZnTe,CZT)衬底上生长中长波双色碲镉汞(HgCdTe,MCT)薄膜材料,生长温度为180℃,研究了双色碲镉汞薄膜材料衬底脱氧技术、分子束外延薄膜生长温度与缓冲层生长等关键技术,实现了中长波双色碲镉汞薄膜生长,外延薄膜采用相差显微镜、扫描电子显微镜(SEM)、傅里叶变换红外光谱仪(FTIR)、二次离子质谱仪(SIMS)及X射线衍射仪(XRD)对薄膜的表面缺陷、厚度、组分及其均匀性、薄膜纵向组分以及晶体质量进行了表征,表面缺陷数量低于600 cm-2,组分(300 K测试)和厚度均匀性分别为?x≤0.001、?d≤0.9μm,X-Ray双晶衍射摇摆曲线FWHM=65 arcsec,得到了质量较高的中长波双色碲镉汞薄膜材料.     

Si基短波碲镉汞材料分子束外延生长研究

报道了在中波工艺基础上,Si 基碲镉汞分子束外延短波工艺的最新研究进展,通过温度标定、使用反射式高能电子衍射、高温计的在线测量和现有的中波 Si 基碲镉汞温度控制曲线建立及优化了 Si 基碲镉汞短波材料的生长温度控制曲线;获得的 Si 基短波 HgCdTe 材料表面光亮、均匀,表面缺陷密度小于3000 cm －2;基于此技术成功制备出了 Si 基短／中波双色材料。     

分子束外延硅基碲镉汞材料技术研究现状

目前,高性能大面阵中波及短波红外探测器已经得到了越来越多的应用。材料参数控制精确、材料质量良好的碲镉汞材料是获得高质量碲镉汞探测器的先决条件。报道了华北光电技术研究所在分子束外延(Molecular Beam Epitaxy, MBE)生长硅基中波及短波碲镉汞材料方面的最新研究进展,并介绍了现阶段MBE生长碲镉汞材料的研究现状。     

分子束外延In掺杂硅基碲镉汞研究

利用分子束外延(Molecular Beam Epitaxy, MBE)系统生长了In掺杂硅基碲镉汞(Mercury Cadmium Telluride, MCT)材料。通过控制In源温度获得了不同掺杂水平的高质量MCT外延片。二次离子质谱仪(Secondary Ion Mass Spectrometer, SIMS)测试结果表明,In掺杂浓度在1×10¹⁵～2×10¹⁶ cm^-3之间。表征了不同In掺杂浓度对MCT外延层位错的影响。发现位错腐蚀坑形态以三角形为主(沿<■>方向排列),且位错密度与未掺杂样品基本相当。对不同In掺杂浓度的材料进行汞饱和低温处理后,样品的电学性能均有所改善。结果表明,In掺杂能够提高材料的均匀性,从而获得较高的电子迁移率。     

Si基大面积碲镉汞分子束外延研究

文章报道了Si基碲镉汞分子束外延(MBE)的最新研究进展。尝试用晶向偏角降低高界面应变能的方法,摸索大失配体系中位错的抑制途径,寻找位错密度与双晶半峰宽的对应关系,基本建立了外延材料晶体质量无损检测评价标准,并对外延工艺进行指导。通过上述研究,15~20μm Si基CdTe复合材料双晶半峰宽最好结果为54arcsec,对应位错密度(EPD)小于2×106/cm2,与相同厚度的GaAs/CdTe(211)双晶水平相当,达到或优于国际最好结果。获得的3 in 10μm Si基HgCdTe材料双晶半峰宽最好结果为51arcsec,目前Si基HgCdTe材料已经初步应用于焦平面中波320×240器件制备。     

低缺陷Si基碲镉汞分子束外延工艺研究

随着焦平面探测器向超大面阵、小像元方向发展,对盲元率尤其连续盲元、均匀性等要求越来越高。材料表面缺陷已经成为抑制Si基碲镉汞分子束外延(Molecular Beam Epitaxial, MBE)技术在更广范围内应用的一个重要因素。通过解决MBE系统束流稳定性、束流测量的精确性和生长温度控制的稳定性共3个MBE生长碲镉汞材料精确控制的关键问题,以及通过正交试验优化生长参数,将Si基碲镉汞材料缺陷密度控制在500 cm^-2以内,最优值达到57.83 cm^-2。     

基于分子束外延的4 in硅基碲镉汞材料工艺研究

现阶段,大面阵碲镉汞红外焦平面探测器的需求持续增加,面向更大尺寸的碲镉汞材料制备技术成为了研究热点。对4 in硅基碲镉汞材料外延技术进行了研究。通过提升设备参数的稳定性、控制外延片的平整度以及优化材料工艺参数等一系列手段,突破了大尺寸硅基碲镉汞材料工艺的关键技术瓶颈,并制备出了高平整度、高均匀性、低缺陷率、高质量的4 in硅基碲镉汞材料。结果表明,该材料的双晶衍射半峰宽小于等于90 arcsec,表面宏观缺陷密度小于等于100 cm^-2,表面平整度小于等于15 μm。     

分子束外延锗基碲镉汞薄膜原位砷掺杂研究

报道了基于Ge衬底分子束外延碲镉汞原位As掺杂材料的研究结果,进行了As掺杂碲镉汞薄膜生长的温度控制研究;分析了As束流对材料晶体质量的影响,结合SIMS测试技术得到了As杂质掺杂浓度与束源炉加热温度的关系;并利用傅里叶红外光谱仪、X射线双晶衍射、EPD检测等手段对晶体质量进行了分析表征,结果显示利用 MBE 方法可以生长出晶体质量良好、缺陷密度低的碲镉汞薄膜;进一步研究了As杂质的激活退火工艺及不同退火条件对材料电学参数的影响。     

分子束外延中波红外碲镉汞原位p-on-n技术研究

研究分析了采用MBE技术外延中波碲镉汞薄膜原位p-on-n材料生长结构及掺杂浓度。掌握了MBE碲镉汞原位p-on-n薄膜材料的生长温度、掺杂浓度和p-n结界面的控制技术,研究了原位p-on-n材料杂质的电学激活退火技术。利用傅里叶变换红外透过测试拟合得到了材料的组分、厚度均匀性,利用X-ray双晶衍射测试结果分析了晶体质量,并统计了材料的EPD值。利用SIMS测试分析了材料中杂质分布状况和浓度,对台面器件I-V特性曲线进行了测试分析。     

3英寸Si基碲镉汞分子束外延工艺研究

随着红外焦平面阵列规模的扩大,由于尺寸和成本的限制,传统晶格匹配的碲锌镉衬底逐渐成为碲镉汞红外焦平面探测器发展的瓶颈,大尺寸、低成本硅基碲镉汞材料应运而生。本文采用分子束外延工艺生长获得了3 in Si基中波碲镉汞薄膜材料,通过采用金相显微镜、傅里叶红外光谱仪、双晶X射线衍射仪、湿化学腐蚀位错密度(EPD)法、Hall测试系统等检测手段对Si基中波碲镉汞分子束外延薄膜材料进行表面、光学、结构和电学性能表征,并采用标准平面器件工艺制备中波640×512焦平面探测阵列进行材料验证,结果表明该材料性能与国际先进水平相当。     

MBE外延InSb基CdTe工艺研究

成功制备了CdTe/InSb复合衬底,为长波HgCdTe外延提供了可能。通过工艺研究解决了InSb氧化层去除及In元素扩散控制两个难点问题,使用As钝化法可以解决双腔衬底转移的问题,在常用的退火工艺下,通过厚度的调整可以阻挡In元素的扩散。     

Si基碲镉汞分子束外延工艺优化研究

报道了Si基碲镉汞(MCT)分子束外延(MBE)的最新研究进展,通过使用反射式高能电子衍射(RHEED)、高温计的在线测量建立和优化了3 in Si基碲镉汞生长温度曲线;通过二次缓冲层的生长进一步降低了界面能,获得的Si基HgCdTe材料在8μm的厚度下半峰宽达到90.72 arcsec,原生片位错密度(EPD)小于1×107 cm-2;采用此材料成功制备出了高性能的中波Si基1280×1024碲镉汞探测器。     

InSb薄膜分子束外延技术研究

InSb材料由于其优异的光电性能,一直是军事领域重要的红外探测器材料。而高温工作是InSb发展的一个重要方向,开发分子束外延InSb材料是实现高温工作的基础。本文采用分子束外延工艺生长获得了高质量的InSb薄膜,通过金相显微镜、X射线双晶衍射仪、原子力显微镜、SEM和EDX等检测手段对InSb外延膜进行表面缺陷、晶体质量表征和分析,并采用标准的InSb器件工艺制备128×128焦平面探测器芯片进行材料的验证,结果表明该材料性能可以满足制备高性能器件的要求。     

Misfit relaxation behavior in CdHgTe layers grown by molecular beam epitaxy on CdZnTe substrates

Uniform layers of cadmium mercury telluride have been grown on inhomogeneous cadmium zinc telluride substrates by molecular beam epitaxy so that a single epitaxial layer experiences a laterally varying lattice mismatch. The lateral variations of layer and substrate lattice parameters, layer lattice tilt, diffraction peak width, etch pit density (EPD) and surface crosshatch have been characterized, and all measured quantities are reported as functions of the substrate lattice parameter. At small mismatch, the layer appears to be elastically deformed. Beyond a certain critical mismatch, the onset of relaxation is clearly observed in the layer lattice parameter. Relaxation leads to appearance of surface crosshatch and an increased diffraction peak width, but a reduction in EPD, suggesting a reduction in the density of threading dislocations within the layer.     

Molecular beam epitaxy growth of high-quality HgCdTe LWIR layers on polished and repolished CdZnTe substrates

We report here molecular beam epitaxy (MBE) mercury cadmium telluride (HgCdTe) layers grown on polished and repolished substrates that showed state-of-the-art optical, structural, and electrical characteristics. Many polishing machines currently available do not take into account the soft semiconductor materials, CdZnTe (CZT) being one. Therefore, a polishing jig was custom designed and engineered to take in account certain physical parameters (pressure, substrate rotational frequency, drip rate of solution onto the polishing pad, and polishing pad rotational velocity). The control over these parameters increased the quality, uniformity, and the reproducibility of each polish. EPIR also investigated several bromine containing solutions used for polishing CZT. The concentration of bromine, as well as the mechanical parameters, was varied in order to determine the optimal conditions for polishing CZT.     

Investigation on the InAS1-xSbx epilayers growth on GaAs (001) substrate by molecular beam epitaxy

Undoped and Be-doped InAs1-xSbx (0 ≤ x ≤ 0.71) epitaxial layers were successfully grown on lattice mismatched semi-insulating GaAs (001) substrate with 2° offcut towards 〈 110〉.The effect of the InAs buffer layer on the quality of the grown layers was investigated.Moreover,the influence of Sb/In flux ratio on the Sb fraction was examined.Furthermore,we have studied the defects distribution along the depth of the InAsSb epilayers.In addition,the p-type doping of the grown layers was explored.The InAsSb layers were assessed by X-ray diffraction,Nomarski microscopy,high resolution optical microscopy and Hall effect measurement.The InAs buffer layer was found to be beneficial for the growth of high quality InAsSb layers.The X-ray analysis revealed a full width at half maximum (FWHM) of 571 arcsec for InAs0.87Sb0.13.It is worth noting here that the Hall concentration (mobility) as low (high) as 5 × 1016 cm-3 (25000 cm2V-1s-1) at room temperature,has been acquired.     

Planar n-on-p ion milled mid-wavelength and long-wavelength infrared diodes on molecular beam epitaxy vacancy-doped CdHgTe on CdZnTe

Planar mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) photodiodes were fabricated by ion milling molecular beam epitaxy (MBE) Cd_xHg_1−xTe (CMT) layers with and without compositional grading in the layer. Linear arrays with 32 and 64 diodes, as well as test diodes of varying size, were fabricated. Good quantum efficiencies were measured, and MWIR diodes, with cutoff wavelength λ_CO=4.5 μm, had zero-bias resistance-area values (R₀A) in excess of 1×10⁷ Ωcm², whereas LWIR diodes with λ_CO=8.9−9.3 μm had R₀A=3×10² Ωcm² at 77 K. Comparison between a limited number of layers indicates that in layers with a gradient the RA values are a factor of ∼10 larger, and possibly more uniform, than in layers without a gradient.     

CdZnTe substrate impurities and their effects on liquid phase epitaxy HgCdTe

Impurity levels were tracked through the stages of substrate and liquid phase epitaxy (LPE) layer processing to identify sources of elements which degrade infrared photodetector performance. Chemical analysis by glow discharge mass spectrometry and Zeeman corrected graphite furnace atomic absorption effectively showed the levels of impurities introduced into CdZnTe substrate material from the raw materials and the crystal growth processes. A new purification process(in situ distillation zone refining) for raw materials was developed, resulting in improved CdZnTe substrate purity. Substrate copper contamination was found to degrade the LPE layer and device electrical properties, in the case of lightly doped HgCdTe. Anomalous HgCdTe carrier type conversion was correlated to certain CdZnTe and CdTe substrate ingots.