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1.
Kai Qiu X.H. Li F. Zhong Z.J. Yin X.D. Luo C.J. Ji Q.F. Han J.R. Chen X.C. Cao X.J. Xie Y.Q. Wang 《Journal of Electronic Materials》2007,36(4):436-441
This paper reports the properties of GaN grown by the hydride vapor-phase epitaxy (HVPE) technique on buffer layers with different
polarities. The N-, mixed-, and Ga-polarity buffer layers were grown by molecular-beam epitaxy (MBE) on sapphire (0001) substrates;
then, thicker GaN epilayers were grown on these by HVPE. The surface morphology, structural, and optical properties of these
HVPE-GaN epilayers were characterized by atomic force microscopy (AFM), x-ray diffraction (XRD), scanning electron microscopy,
and photoluminescence (PL) spectroscopy. The results indicate that the crystallinity of these HVPE-GaN epilayers depends on
the polarity of the buffer layer. 相似文献
2.
3.
LPE HgCdTe on sapphire status and advancements 总被引:3,自引:0,他引:3
G. Bostrup K. L. Hess J. Ellsworth D. Cooper R. Haines 《Journal of Electronic Materials》2001,30(6):560-565
With the evolution of infrared arrays to over four million pixels, larger formats have demanded higher quality mercury cadmium
telluride (MCT) wafers. Since single defects can easily degrade multiple diodes, high operability requires very homogeneous
and nearly flawless epitaxial surfaces. Subsequent photolithography and hybridization also demand unprecedented levels of
substrate flatness and low imperfections. To consistently and reliably produce large area arrays, Insaco Inc., The Boeing
Company, and Rockwell International Corporation have developed major quality improvement procedures which address all three
components of the infrared material wafer architecture. Centered on the producible alternative to cadmium telluride for epitaxy
(PACE) process, technological advancements encompassed sapphire substrates, organometallic vapor phase epitaxy (OMVPE), cadmium
telluride (CdTe) buffer layer growth, and liquid phase epitaxial (LPE) mercury cadmium telluride growth. Processed material
from these runs mated to Conexant™ fabricated multiplexers have successfully produced 1024 1024 and the first 2048 2048 IR short-wave (2.5 m at 80 K) hybrid
focal plane arrays. Operabilities in these implanted n-on-p junction devices reach 99.98% with near 70% quantum efficiency
in the astronomy ‘K’ band (2.2–2.4 microns). 相似文献
4.
报道了基于分子束外延(Molecular Beam Epitaxy, MBE)碲镉汞(Mercury Cadmium Telluride, MCT)技术的大幅宽、多谱段、大像元高光谱红外探测器的最新研究进展。采用MBE技术制备出高质量MCT材料;采用成熟的n-on-p技术路线制备探测芯片,并针对特殊形状的大像元进行了优化;高光谱专用读出电路设计针对短波、窄谱段、小信号等典型特征进行了优化,并针对光谱应用加入行增益可调等功能设计。测试结果表明,组件基本性能良好,有效像元率大于99.5%,平均量子效率优于70%。 相似文献
5.
C. D. Maxey M. U. Ahmed C. L. Jones R. A. Catchpole P. Capper N. T. Gordon M. Houlton T. Ashley 《Journal of Electronic Materials》2001,30(6):723-727
Uncooled operation of Auger suppressed fully doped mercury cadmium telluride (MCT) devices designed by Ashley and Elliott1 and grown by metalorganic vapor phase epitaxy (MOVPE) by Maxey et al.2 has been demonstrated. These devices also demonstrate efficient negative luminescent emission in the long wavelength infrared
(LWIR) spectra.3 However, to operate a large area device (>1 cm2) requires a large current (∼10 A), and consequently, it is critical that the series resistance is minimized. To increase
optical efficiency, deep optical concentrators are needed. Similar InSb molecular beam epitaxy (MBE) devices utilize a highly
doped InSb substrate which allows a conduction path into the substrate with reduced series resistance and acts as an optical
window (due to Moss-Burstein shift) allowing transmission of the 6 m IR emission. A suitable high conductivity substrate for
MCT emitter devices is required to have a sheet resistivity of <1 /□. The conventional MCT epitaxy substrates are CdZnTe and
GaAs. High conductivity cadmium zinc telluride (CZT) was not found to be commercially available. Although high conductivity,
n-type GaAs is available, the maximum doping is limited by the degree of free carrier absorption in the LWIR which would reduce
the potential emitter efficiency. This paper describes a novel investigation into achieving working LW emitter devices with
deep mesas in which the current is carried by the GaAs substrate. The key issue which had to be addressed was obtaining conduction
between the II/VI and III/V materials. A variety of interface designs was investigated but the best results were achieved
by minimizing the band-gap of the interfacial II/VI MCT and optimizing the properties of the top region of the GaAs substrate. 相似文献
6.
Influence of Substrate Orientation on the Growth of HgCdTe by Molecular Beam Epitaxy 总被引:1,自引:0,他引:1
An empirical study is reported, wherein HgCdTe was deposited simultaneously on multiple CdZnTe substrates of different orientations
by molecular beam epitaxy. These orientations included the following vicinal surfaces: (115)B, (113)B, (112)B, and (552)B.
Additionally, growth on (111)B was explored. Growth conditions found to be nearly optimalfor the standard (112)B orientation
were selected. Through a series of growth runs, substrate temperature was varied, and the physical properties of the resulting
HgCdTe epilayers were measured. These measurements included Nomarski microscopy, infrared transmission, x-ray diffraction,
and defect decoration etching. The properties of HgCdTe epilayers as a function of temperature were roughly similar for all
vicinal surfaces. Namely, as the temperature increased, the dislocation density decreased. At some critical temperature, the
density of void defects increased dramatically. This critical temperature varied with orientation, the (115)B exhibiting the
lowest critical temperature and the (112)B and (552)B exhibiting the highest. The (115)B, (113)B, and (112)B orientations
exhibited “needlelike” defects on the as-grown HgCdTe surface. The density of these defects decreased with increasing temperature.
The (552)B surface exhibited no such defects and growth behavior nearly identical to the (112)B growthsurface. 相似文献
7.
碲镉汞外延材料缺陷的研究进展 总被引:1,自引:1,他引:0
通过对近年来的部分国外文献进行归纳分析,介绍了碲镉汞(MCT)缺陷研究的现状.与其他类似的半导体相比,MCT以其显著的优势成为红外焦平面(FPA)器件中最为常用的窄带隙材料.MCT外延层中的缺陷可能会影响光敏元的性能,降低MCT焦平面器件的可用性.衬底类型、衬底晶向和生长期间的衬底温度等因素对MCT外延层的质量有明显影... 相似文献
8.
9.
用电子束蒸发方法在Si(111)衬底上蒸发了Au/Cr和Au/Ti/Al/Ti 两种金属缓冲层,然后在金属缓冲层上用气源分子束外延(GSMBE)生长GaN. 两种缓冲层的表面都比较平整和均匀,都是具有Au(111)面择优取向的立方相Au层. 在Au/Cr/Si(111)上MBE生长的GaN,生长结束后出现剥离. 在Au/Ti/Al/Ti/Si(111)上无AlN缓冲层直接生长GaN,得到的是多晶GaN;先在800℃生长一层AlN缓冲层,然后在710℃生长GaN,得到的是沿GaN(0001)面择优取向的六方相GaN. 将Au/Ti/Al/Ti/Si(111)在800℃下退火20min,金属层收缩为网状结构,并且成为多晶,不再具有Au(111)方向择优取向. 相似文献
10.
11.
研究了Si缓冲层对选区外延Si基Ge薄膜的晶体质量的影响。利用超高真空化学气相沉积系统,结合低温Ge缓冲层和选区外延技术,通过插入Si缓冲层,在Si/SiO_2图形衬底上选择性外延生长Ge薄膜。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、原子力显微镜(AFM)表征了Ge薄膜的晶体质量和表面形貌。测试结果表明,选区外延Ge薄膜的晶体质量比无图形衬底外延得到薄膜的晶体质量要高;选区外延Ge薄膜前插入Si缓冲层得到Ge薄膜具有较低的XRD曲线半高宽以及表面粗糙度,位错密度低至5.9×10~5/cm^2,且薄膜经过高低温循环退火后,XRD曲线半高宽和位错密度进一步降低。通过插入Si缓冲层可提高选区外延Si基Ge薄膜的晶体质量,该技术有望应用于Si基光电集成。 相似文献
12.
13.
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。 相似文献
14.
Muhammad Iqbal Bakti Utama Maria de la Mata Cesar Magen Jordi Arbiol Qihua Xiong 《Advanced functional materials》2013,23(13):1636-1646
Twinning, polytypism, and polarity are important aspects in nanostructural growth since their presence can affect various properties of the as‐grown products. The morphology of nanostructures grown via van der Waals epitaxy is shown to be strongly influenced by the twinning density and the presence of polytypism within the nanostructures, while the growth direction is driven by the compound polarity. With ZnTe as the model material, vertically aligned nanorods are successfully produced with variable cross‐section and branched crystals (tripods and tetrapods) on only a single type of substrate. Van der Waals epitaxy contributes by relaxing the lattice‐mismatch requirements for epitaxial growth and by enabling a variety of crystal planes in the initial stages of the growth to be interfaced to the substrate, regardless of the polarity of the epitaxial material. These results may provide more flexibility in tuning rationally the morphology of epitaxial nanostructures into other shapes with higher complexity by routine adjustment of growth environment. 相似文献
15.
B. L. Williams H. G. Robinson C. R. Helms N. Zhu 《Journal of Electronic Materials》1997,26(6):600-605
Junction formation by ion implantation is a critical step in producing high quality infrared focal plane arrays in mercury
cadmium telluride (MCT). We have analyzed the structural properties of MCT implanted with B at doses of 1014 and 1015 cm−2 using double and triple crystal x-ray diffraction (DCD and TCD) to monitor the disorder and strain of the implanted region
as a function of processing conditions. TCD (333) reflections show that a distinct tensile peak is produced by the high dose
implant while the low dose implant shows only a low angle shoulder on the substrate peak. A preliminary association of the
low angle shoulder with point defects has been made since no extended defects have been observed in the low dose range. For
the high dose implant, extended defect formation has been reported and may be responsible for the tensile peak. After annealing,
the low angle shoulder on the low dose implant has disappeared, while the high dose implant exhibits an increase in the tensile
strain from 6.5 × 10−4 to 9.3 × 10−4 after 24 h of annealing and then decreases in tensile strain to 7.3 × 10−4 after 48 h of annealing. It is believed the changes in strain are associated with the Oswald ripening and dissolution of
extended defects, which has been observed during annealing of ion implanted Si. 相似文献
16.
C. D. Maxey J. P. Camplin I. T. Guilfoy J. Gardner R. A. Lockett C. L. Jones P. Capper M. Houlton N. T. Gordon 《Journal of Electronic Materials》2003,32(7):656-660
A new metal-organic vapor-phase epitaxial (MOVPE) reactor-cell design has been developed to grow on 3-in.-diameter substrates.
This was required to produce uniform, fully doped heterostructures needed for array producibility and wafer-scale processing
compatibility. The reactor has demonstrated epitaxial growth of HgCdTe (MCT) with good morphology onto both GaAs and GaAs
on Si wafers. The density of surface-growth defects, typical of MOVPE growth, has been reduced to <5 cm−2 at a sufficient yield to make the production of low cluster-defect, two-dimensional (2-D) arrays possible. The new horizontal
reactor cell uses substrate rotation to achieve improved uniformity and is able to incorporate substrates up to 4-in. diameter.
Good compositional and thickness uniformity was achieved on epilayers grown on 3-in.-diameter, low-cost GaAs and GaAs on Si
wafers. Sufficient uniformity has been achieved to produce 12 sites of full-TV format 2-D arrays per slice. To yield the benefits
of heterostructure design, the MCT epilayers also needed to demonstrate efficient and uniform activation of both arsenic (acceptor)
and iodine (donor) dopants. Secondary ion mass spectrometry (SIMS) and Hall assessment showed that the uniformity of As and
I doping was ±10%. Fully doped heterostructures have been grown to investigate the device performance in the 3–5 μm and 8–12
μm infrared bands. The 2-D array performance has shown that at 180 K near-background-limited performance (BLIP) diodes have
been produced in the 3–5 μm band. 相似文献
17.
P. Mitra F. C. Case H. L. Glass V. M. Speziale J. P. Flint S. P. Tobin P. W. Norton 《Journal of Electronic Materials》2001,30(6):779-784
We report the growth of HgCdTe on (552)B CdZnTe by metalorganic vapor phase epitaxy (MOVPE). The (552) plane is obtained by
180 rotation of the (211) plane about the [111] twist axis. Both are 19.47 degrees from (111), but in opposite directions.
HgCdTe grown on the (552)B-oriented CdZnTe has a growth rate similar to the (211)B, but the surface morphology is very different.
The (552)B films exhibit no void defects, but do exhibit ∼40 μm size hillocks at densities of 10–50 cm−2. The hillocks, however, are significantly flatter and shorter than those observed on (100) metalorganic vapor phase epitaxy
(MOVPE) HgCdTe films. For a 12–14 μm thick film the height of the highest point on the hillock is less than 0.75 μm. No twinning
was observed by back-reflection Laue x-ray diffraction for (552)B HgCdTe films and the x-ray double crystal rocking curve
widths are comparable to those obtained on (211)B films grown side-by-side and with similar alloy composition. Etch pit density
(EPD) measurements show EPD values in the range of (0.6–5)×105 cm−2, again very similar to those currently observed in (211)B MOVPE HgCdTe. The transport properties and ease of dopant incorporation
and activation are all comparable to those obtained in (211)B HgCdTe. Mid-wave infrared (MWIR) photodiode detector arrays
were fabricated on (552)B HgCdTe films grown in the P-n-N device configuration (upper case denotes layers with wider bandgaps).
Radiometric characterization at T=120–160 K show that the detectors have classical spectral response with a cutoff wavelength
of 5.22 μm at 120 K, quantum efficiency ∼78%, and diffusion current is the dominant dark current mechanism near zero bias
voltage. Overall, the results suggest that (552)B may be the preferred orientation for MOVPE growth of HgCdTe on CdZnTe to
achieve improved operability in focal plane arrays. 相似文献
18.
Direct growth of CdZnTe/Si substrates for large-area HgCdTe infrared focal plane arrays 总被引:1,自引:0,他引:1
S. M. Johnson T. J. de Lyon C. A. Cockrum W. J. Hamilton T. Tung F. I. Gesswein B. A. Baumgratz L. M. Ruzicka O. K. Wu J. A. Roth 《Journal of Electronic Materials》1995,24(5):467-473
Direct epitaxial growth of high-quality 100lCdZnTe on 3 inch diameter vicinal {100}Si substrates has been achieved using molecular
beam epitaxy (MBE); a ZnTe initial layer was used to maintain the {100} Si substrate orientation. The properties of these
substrates and associated HgCdTe layers grown by liquid phase epitaxy (LPE) and subsequently processed long wavelength infrared
(LWIR) detectors were compared directly with our related efforts using CdZnTe/ GaAs/Si substrates grown by metalorganic chemical
vapor deposition (MOCVD). The MBE-grown CdZnTe layers are highly specular and have both excellent thickness and compositional
uniformity. The x-ray full-width at half-maximum (FWHM) of the MBE-grown CdZnTe/Si increases with composition, which is a
characteristic of CdZnTe grown by vapor phase epitaxy, and is essentially equivalent to our results obtained on CdZnTe/GaAs/Si.
As we have previously observed, the x-ray FWHM of LPE-grown HgCdTe decreases, particularly for CdZnTe compositions near the
lattice matching condition to HgCdTe; so far the best value we have achieved is 54 arc-s. Using these MBE-grown substrates,
we have fabricated the first high-performance LWIR HgCdTe detectors and 256 x 256 arrays using substrates consisting of CdZnTe
grown directly on Si without the use of an intermediate GaAs buffer layer. We find first that there is no significant difference
between arrays fabricated on either CdZnTe/Si or CdZnTe/GaAs/Si and second that the results on these Si-based substrates are
comparable with results on bulk CdZnTe substrates at 78K. Further improvements in detector performance on Si-based substrates
require a decrease in the dislocation density. 相似文献
19.
K. D. Maranowski J. M. Peterson S. M. Johnson J. B. Varesi A. C. Childs R. E. Bornfreund A. A. Buell W. A. Radford T. J. de Lyon J. E. Jensen 《Journal of Electronic Materials》2001,30(6):619-622
HgCdTe p-on-n double layer heterojunctions (DLHJs) for mid-wave infrared (MWIR) detector applications have been grown on 100
mm (4 inch) diameter (211) silicon substrates by molecular beam epitaxy (MBE). The structural quality of these films is excellent,
as demonstrated by x-ray rocking curves with full widths at half maximum (FWHMs) of 80–100 arcsec, and etch pit densities
from 1 106 to 7 106 cm−2. Morphological defect densities for these layers are generally less than 1000 cm−2. Improving Hg flux coverage of the wafer during growth can reduce void defects near the edges of the wafers. Improved tellurium
source designs have resulted in better temporal flux stability and a reduction of the center to edge x-value variation from
9% to only 2%. Photovoltaic MWIR detectors have been fabricated from some of these 100mm wafers, and the devices show performance
at 140 K which is comparable to other MWIR detectors grown on bulk CdZnTe substrates by MBE and by liquid phase epitaxy. 相似文献
20.
High-Performance LWIR MBE-Grown HgCdTe/Si Focal Plane Arrays 总被引:1,自引:0,他引:1
Richard Bornfreund Joe P. Rosbeck Yen N. Thai Edward P. Smith Daniel D. Lofgreen Mauro F. Vilela Aimee A. Buell Michael D. Newton Kenneth Kosai Scott M. Johnson Terry J. de Lyon John E. Jensen Meimei Z. Tidrow 《Journal of Electronic Materials》2007,36(8):1085-1091
We have been actively pursuing the development of long-wavelength infrared (LWIR) HgCdTe grown by molecular beam epitaxy (MBE)
on large-area silicon substrates. The current effort is focused on extending HgCdTe/Si technology to longer wavelengths and
lower temperatures. The use of Si versus bulk CdZnTe substrates is being pursued due to the inherent advantages of Si, which
include available wafer sizes (as large as 300 mm), lower cost (both for the substrates and number of die per wafer), compatibility
with semiconductor processing equipment, and the match of the coefficient of thermal expansion with silicon read-out integrated
circuit (ROIC). Raytheon has already demonstrated low-defect, high-quality MBE-grown HgCdTe/Si as large as 150 mm in diameter.
The focal plane arrays (FPAs) presented in this paper were grown on 100 mm diameter (211)Si substrates in a Riber Epineat
system. The basic device structure is an MBE-grown p-on-n heterojunction device. Growth begins with a CdTe/ZnTe buffer layer followed by the HgCdTe active device layers; the entire
growth process is performed in␣situ to maintain clean interfaces between the various layers. In this experiment the cutoff wavelengths were varied from 10.0 μm to 10.7 μm at 78 K. Detectors with >50% quantum efficiency and R
0
A ∼1000 Ohms cm2 were obtained, with 256 × 256, 30 μm focal plane arrays from these detectors demonstrating response operabilities >99%.
Work supported by the Missile Defense Agency (MDA) through CACI Technologies, Inc. subcontract no. 601-05-0088, NVESD technical
task order no. TTO-01, prime contract no. DAAB07-03-D-C214, (delivery order no. 0016) 相似文献