共查询到20条相似文献,搜索用时 15 毫秒
1.
Jae Jin Kim R. N. Jacobs L. A. Almeida M. Jaime-Vasquez C. Nozaki David J. Smith 《Journal of Electronic Materials》2013,42(11):3142-3147
A microstructural study of HgCdTe/CdTe/GaAs(211)B and CdTe/GaAs(211)B heterostructures grown using molecular beam epitaxy (MBE) was carried out using transmission electron microscopy and small-probe microanalysis. High-quality MBE-grown CdTe on GaAs(211)B substrates was demonstrated to be a viable composite substrate platform for HgCdTe growth. In addition, analysis of interfacial misfit dislocations and residual strain showed that the CdTe/GaAs interface was fully relaxed except in localized regions where GaAs surface polishing had caused small pits. In the case of HgCdTe/CdTe/GaAs(211)B, the use of thin HgTe buffer layers between HgCdTe and CdTe for improving the HgCdTe crystal quality was also investigated. 相似文献
2.
CdTe/GaAs是HgCdTe分子束外延的重要替代衬底材料。用X双晶衍射和光致发光测试研究了分子束外延生长的CdTe(211)B/GaAs(211)B的晶体结构质量,表明外延膜晶体结构完整,具有很高的质量。用高分辨率的透射电镜研究其界面特性,观察到CdTe(211)B相对于GaAs(211)B向着[111]方向倾斜一个小角度(约3°),界面的四面体键网发生扭曲,由于晶格失配,在界面存在很高的失配位错密度。用二次离子质谱分析仪分析了GaAs衬底中的Ga和As向CdTe外扩散的情况。结果表明:如果要在GaAs衬底上生长HgCdTe外延膜,必须先生长一层具有一定厚度的CdTe来阻止Ga和As向HgCdTe的外扩散和失配位错的延伸。 相似文献
3.
文章利用高分辨率X射线衍射技术对分子束外延CdTe(211)B/Si(211)材料的CdTe外延薄膜进行了倒易点二维扫描,并通过获得的对称衍射面和非对称衍射面的倒易空间图,对CdTe外延层的剪切应变和正应变状况进行了分析.研究发现,对于CdTe/Si结构,随着CdTe厚度的增加,[1-1-1]、[01-1]两个方向的剪切角γ[1-1-1]和λ[01-1]都有变小的趋势,且γ[1-1-1]的大小约为γ[01-1]的两倍;对于CdTe/ZnTe/Si,ZnTe缓冲层的引入可以有效地降低CdTe层的剪切应变.CdTe层的正应变表现为张应变,主要来源于CdTe和Si的热膨胀系数存在差异,而在从生长温度280℃降至室温20℃的过程产生的热应变. 相似文献
4.
S. R. Rao S. S. Shintri J. K. Markunas R. N. Jacobs I. B. Bhat 《Journal of Electronic Materials》2010,39(7):996-1000
High-quality (211)B CdTe buffer layers on Si substrates are required to enable Hg1–x
Cd
x
Te growth and device fabrication on lattice-mismatched Si substrates. Metalorganic vapor-phase epitaxy (MOVPE) of (211)B CdTe
on Si substrates using Ge and ZnTe interlayers has been achieved. Cyclic annealing has been used during growth of thick CdTe
layers in order to improve crystal quality. The best (211)B CdTe/Si films grown in this study display a low x-ray diffraction
(XRD) rocking-curve full-width at half-maximum (FWHM) of 85 arcsec and etch pit density (EPD) of 2 × 106 cm−2. These values are the best reported for MOVPE-grown (211) CdTe/Si and are comparable to those for state-of-the-art molecular
beam epitaxy (MBE)-grown CdTe/Si. 相似文献
5.
本文主要分析了作为分子束外延碲镉汞的碲锌镉衬底的表面预处理工艺.湿化学处理工艺主要目的是去除衬底表面损伤层,0.5%溴甲醇溶液的腐蚀速率为7 nm/s,但腐蚀的同时会形成表面富Te层和氧化层,氧化层的厚度随溴甲醇的浓度增加而增加;高温热处理工艺主要是消除湿化学腐蚀形成的富Te层和氧化层,340℃的高温处理可去除表面氧化层;也可以直接通过回旋共振等离子体处理衬底表面,形成化学计量比正常的干净表面. 相似文献
6.
Giacomo Badano Patrice Gergaud Ivan C. Robin Xavier Baudry Benoît Amstatt Fréderique Gemain 《Journal of Electronic Materials》2010,39(7):908-911
We have used x-ray diffraction to assess the thickness dependence of strain in molecular-beam epitaxial (MBE) CdTe(211)/Ge(211).
For 25-nm-thick layers, we find tensile stress of 100 MPa and in-plane strain of ~1.5 × 10−3. This stress relaxes during growth and becomes zero beyond 1 μm. We use the Dunn and Koch formula to estimate the threading dislocation density from the full-width at half-maximum of the
(224) rocking curve. We then estimate the annihilation radius of MBE-grown CdTe(211)B/Ge(211) to be ~10 nm. Our layers have
etch pit densities between 5 × 107 cm−2 and 5 × 106 cm−2 for a thickness of 10 μm. The lowest densities were obtained by periodic annealing epitaxy. We discuss mechanisms for the saturation of the dislocation
density. 相似文献
7.
8.
S. R. Rao S. S. Shintri J. K. Markunas R. N. Jacobs I. B. Bhat 《Journal of Electronic Materials》2011,40(8):1790-1794
High-quality (211)B CdTe buffer layers are required during Hg1−x
Cd
x
Te heteroepitaxy on Si substrates. In this study, direct metalorganic vapor-phase epitaxy (MOVPE) of (211)B CdTe on Si, as
well as CdTe on Si using intermediate Ge and ZnTe layers, has been achieved. Tertiary butyl arsine was used as a precursor
to enable As surfactant action during CdTe MOVPE on Si. The grown CdTe/Si films display a best x-ray diffraction rocking-curve
full-width at half-maximum of 64 arc-s and a best Everson etch pit density of 3 × 105 cm−2. These values are the best reported for MOVPE-grown (211)B CdTe/Si and match state-of-the-art material grown using molecular-beam
epitaxy. 相似文献
9.
P-Type doping with arsenic in (211)B HgCdTe grown by MBE 总被引:1,自引:0,他引:1
P. S. Wijewarnasuriya S. S. Yoo J. P. Faurie S. Sivananthan 《Journal of Electronic Materials》1996,25(8):1300-1305
Arsenic incorporation and doping in HgCdTe layers grown by molecular beam epitaxy (MBE) were examined in this paper. Arsenic
incorporation into MBE-HgCdTe was carried out in two different ways: (1)ex-situ arsenic ion-implantation on indium-doped n-type HgCdTe layers, and (2) through a new approach called arsenic planar doping.
We report onex-situ arsenic diffusion on indiumdoped MBE-HgCdTe layers at 450°C. In the investigated layers, arsenic redistribution occurs with
a multi-component character. We obtained a diffusion coefficient of DAs = (1-3) × 10−13 cm2/s at 450°C. Results of differential Hall and fabricated p-n junctions suggest that during high temperature annealing, arsenic
preferentially substitutes into Te sublattices and acts as acceptor impurities. In the second case, arsenic has been successfully
incorporated during the MBE growth as an acceptor in the planar doping approach. Withoutex-situ annealing, as-grown layers show up to 50% activation of arsenic during the growth. These results are very promising forin-situ fabrication of infrared devices using HgCdTe material. 相似文献
10.
Si基CdTe复合衬底分子束外延研究 总被引:1,自引:0,他引:1
文章引入晶格过渡的Si/ZnTe /CdTe作为复合外延基底材料,以阻挡Si/HgCdTe之间大晶格失配产生的高密度位错。通过对低温表面清洁化、面极性控制和孪晶抑制等的研究,解决了Si基CdTe分子束外延生长中诸多的技术难题。在国内首次采用分子束外延(MBE)的方法获得了大面积的Si基CdTe复合衬底材料,对应厚度为4~4. 4μm Si/CdTe (211)样品双晶半峰宽的统计平均结果为83弧秒,与相同厚度的GaAs/CdTe (211)双晶平均水平相当。 相似文献
11.
HgCdTe材料的表面缺陷是造成探测器性能下降的主要原因之一。采用聚焦离子束(Focused Ion Beam, FIB)、扫描电子显微镜(Scanning Electron Microscope, SEM)和能量色散X射线光谱仪(Energy Dispersive X-ray Spectrometer, EDX)研究了碲锌镉(CdZnTe)基HgCdTe外延层的表面缺陷。通过分析不同类型缺陷形成的原因,确定缺陷起源于HgCdTe材料生长过程。缺陷的形状与生长条件关系密切。凹坑及火山口状缺陷与Hg缺乏/稍高生长温度、分子束源坩埚中材料形状变化造成的不稳定束流有关。金刚石状缺陷和火山口状/金刚石状复合缺陷的产生与Hg/Te高束流比、低生长温度相关。在5 cm×5 cm大小的CdZnTe(211)B衬底表面上生长出了组分为0.216、厚度约为6.06~7 μm的高质量HgCdTe外延层。同时还建立了缺陷类型与HgCdTe薄膜生长工艺的关系。该研究对于制备高质量HgCdTe/CdZnTe外延层具有参考意义。 相似文献
12.
Characterization of cross-hatch morphology of MBE (211) HgCdTe 总被引:2,自引:0,他引:2
M. Martinka L. A. Almeida J. D. Benson J. H. Dinan 《Journal of Electronic Materials》2001,30(6):632-636
We present the results of a detailed study of the nature and origin of cross-hatch patterns commonly observed on (211) HgCdTe
epilayers deposited by molecular beam epitaxy. Cross-hatch patterns were examined using x-ray topography as well as Nomarski,
interferometric, and atomic force microscopies. Cross-hatch patterns were generally comprised of three sets of lines, parallel
to the [231],, [213], and [011] directions. The lines parallel to the [011] direction exhibited distinct properties compared
to the two sets of lines parallel to [231] and [213]. Under growth conditions characterized by excessive Hg flux (low temperature),
lines parallel to [011] were periodic and tended to dominate the cross-hatch pattern. In some cases, bands of dislocations,
10–100 m in width, formed parallel to [011]. Under optimized growth conditions, on very closely lattice-matched substrates,
(dislocation densities <105 cm−2) lines parallel to [011] vanished entirely, and lines parallel to [231] and [213] became sparse. The remaining lines were
typically fragments terminated by either a single dislocation, a cluster of dislocations (micro-void), or the wafer's edge.
The density of these line fragments tended to decrease as the dislocation density decreased. Under the best growth conditions
on very closely lattice-matched substrates we have achieved dislocation densities of 5 104 cm−2, which is comparable to the dislocation density of the CdZnTe substrate. 相似文献
13.
14.
J. D. Benson L. O. Bubulac C. M. Lennon R. N. Jacobs P. J. Smith J. K. Markunas M. Jaime-Vasquez L. A. Almeida A. Stoltz J. A. Arias G. Brill Y. Chen P. S. Wijewarnasuriya M. F. Vilela J. Peterson S. M. Johnson D. D. Lofgreen D. Rhiger E. A. Patten J. Bangs 《Journal of Electronic Materials》2013,42(11):3217-3223
The crystalline structure and impurity profiles of HgCdTe/CdTe/alternate substrate (AS; Si and GaAs are possibilities) and CdTe/AS were analyzed by secondary-ion mass spectrometry, atomic force microscopy, etch pit density analysis, and scanning transmission electron microscopy. Impurities (Li, Na, and K) were shown to getter in as-grown CdTe/Si epilayers at in situ Te-stabilized thermal anneal (~500°C) interfaces. In HgCdTe/CdTe/Si epilayers, indium accumulation was observed at Te-stabilized thermal anneal interfaces. Impurity accumulation was measured at HgCdTe/CdTe and CdTe/ZnTe interfaces. Processing anneals were found to nearly eliminate the gettering effect at the in situ Te-stabilized thermal anneal interfaces. Impurities were found to redistribute to the front HgCdTe/CdTe/Si surface and p–n junction interfaces during annealing steps. We also investigated altering the in situ Te-stabilized thermal anneal process to enhance the gettering effect. 相似文献
15.
We study the adsorption of Hg on CdTe(211)B using an 88-wavelength spectroscopic ellipsometer mounted on a commercial, molecular
beam epitaxy (MBE) chamber. A detailed analysis of the pseudo-dielectric function shows that Hg is present at the surface
both in chemisorbed and physisorbed form. Effective medium models for a mixture of chemisorbed and physisorbed Hg on the microscopically
rough CdTe surface could not fit our data. However, a proposed model in which a partial layer of physisorbed Hg sits on top
of a partial layer of chemisorbed Hg fits the measured pseudo-dielectric function well and yields precise values for the thicknesses
of the chemisorbed and the physisorbed Hg layers. These values change in the expected manner as a function of Hg flux, temperature,
and Te coverage. An analysis of the uncertainty in the measured thicknesses is carried out in detail, and a study of the limitations
of the ellipsometer used for this study is presented. The effects of these limitations on the precision and accuracy of in-situ
data are enumerated. 相似文献
16.
17.
分子束外延碲镉汞技术是制备第三代红外焦平面探测器的重要手段,基于异质衬底的碲镉汞材料具有尺寸大、成本低、与常规半导体设备兼容等优点,是目前低成本高性能红外探测器发展中的研究重点。对异质衬底上碲镉汞薄膜位错密度随厚度的变化规律进行了建模计算,结果显示ρ~1/h 模型与实验结果吻合度好,异质衬底上原生碲镉汞薄膜受位错反应半径制约,其位错密度无法降低至 5×106cm-2以下,难以满足长波、甚长波器件的应用需求。为了有效降低异质外延的碲镉汞材料位错密度,近年来出现了循环退火、位错阻挡和台面位错吸除等位错抑制技术,本文介绍了各技术的原理及进展,分析了后续发展趋势及重点。循环退火和位错阻挡技术突破难度大,发展潜力小,难以将碲镉汞位错密度控制在 5×105cm-2以内。台面位错吸除技术目前已经显示出了巨大的发展潜力和价值,后续与芯片工艺融合后,有望大幅促进低成本长波、中长波、甚长波器件的发展。 相似文献
18.
19.
利用高分辨率X射线衍射技术对分子束外延CdTe(211)B/Si(211)材料的CdTe外延薄膜进行了倒易点二维扫描,并通过获得的对称衍射面和非对称衍射面的倒易空间图,对CdTe缓冲层的剪切应变状况进行了分析.研究发现,对于CdTe/Si结构,随着CdTe厚度的增加,[1-1-1]、[01-1]两个方向的剪切角γ[1-1-1]和γ[01-1]都有变小的趋势,且γ[1-1-1]的大小约为γ[01-1]的两倍;对于CdTe/ZnTe/Si结构,ZnTe缓冲层的引入可以有效地降低CdTe层的剪切应变. 相似文献
20.
Shashidhar Shintri Sunil Rao Priyalal Wijewarnasuriya Sudhir Trivedi Ishwara Bhat 《Journal of Electronic Materials》2012,41(10):2824-2827
We report on the investigation of epitaxial cadmium telluride grown by metalorganic vapor-phase epitaxy (MOVPE) on (211)Si, with particular emphasis on studying the effect of changing the reactor parameters and thermal annealing conditions on the epilayer quality. The CdTe films were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and x-ray diffraction (XRD). The best CdTe films were observed when the Te/Cd precursor partial pressure ratio was close to 3.1. It was also observed that, though annealing improved the crystal quality, a slight increase in surface roughness was observed. Similar attempts were made to improve the growth conditions of ZnTe intermediate buffer layer, which showed similar trends with changes in precursor flows. 相似文献