共查询到20条相似文献,搜索用时 15 毫秒
1.
P. S. Wijewarnsuriya M. Zandian D. D. Edwall W. V. McLevige C. A. Chen J. G. Pasko G. Hildebrandt A. C. Chen J. M. Arias A. I. D’Souza S. Rujirawat S. Sivananthan 《Journal of Electronic Materials》1998,27(6):546-549
The capability of growing state-of-the-art middle wavelength infrared (MWIR)-HgCdTe layers by molecular beam epitaxy (MBE)
on large area silicon substrates has been demonstrated. We have obtained excellent compositional uniformity with standard
deviation of 0.001 with mean composition of 0.321 across 1.5″ radii. R0A as high as 5 × 107 ω-cm2 with a mean value of 7 × 106 Θ-cm2 was measured for cut-off wavelength of 4.8 μm at 77K. Devices exhibit diffusion limited performance for temperatures above
95K. Quantum efficiencies up to 63% were observed (with no anti-reflection coating) for cut-off wavelength (4.8–5.4) μm @
77K. Excellent performance of the fabricated photodiodes on MBE HgCdTe/CdTe/Si reflects on the overall quality of the grown
material in the MWIR region. 相似文献
2.
V. Rao H. Ehsani I. B. Bhat M. Kestigian R. Starr M. H. Weiler M. B. Reine 《Journal of Electronic Materials》1995,24(5):437-443
We report arsenic doping of Hg1-xCdxTe (0.2 < x < 0.3) grown using metalorganic vapor phase epitaxy (MOVPE) by the direct alloy growth (DAG) technique. Tertiarybutylarsine
(TBAs) was used as a precursor for As doping. Several epilayers were grown at different Hg partial pressures and TBAs bubbler
temperatures in order to study the doping characteristics. The amount of As incorporated in the layer as well as the acceptor
concentration were found to be a strong function of the Hg pressure. Secondary ion mass spectrometric studies on heterostructures
showed that the compositional interdiffusion is less than the diffusion of As during growth. P-N junctions were grown using
TBAs for the first time and several of these layers were processed to fabricate photodiodes. A p-on-n grown junction photodiode
with a cutoff wavelength of 8.2 μm had an RoA value of 241 ohm-cm2 at 80K and is the highest reported value for p-on-n DAG-MOVPE devices. Methods to improve the device RoA of the grown junctions are also proposed. 相似文献
3.
4.
S. Perkowitz 《Journal of Electronic Materials》1985,14(5):551-562
Far infrared (10 to 250 cm−1) reflection and transmission spectroscopy is used to characterize the free-carrier and alloy properties of the leading infrared
detector material Hg1-xCdxTe and the substrate materials CdTe and CdZnTe. The data yield values for carrier concentration and mobility, the compositional
parameter x and film thickness which generally agree with other determinations. The advantages of this contactless nondestructive
technique are described. Applications to the newly proposed infrared detector material Hg1-xMnxTe are briefly reviewed. 相似文献
5.
Single crystal epitaxial layers of Hg1-x
Cd
x
Te were grown on CdTe substrates employing the chemical vapor transport technique. Different growth temperatures, substrate
orientations, and various pressures of Hgl2 as a transport agent were used while the source materials had a fixed composition ofx = 0.2. The epilayers are of nearly uniform composition to a depth of about one-half of the layer thickness. Chemical etching
of the as-grown epilayers revealed low etch pit densities in the range of 103–104 cm−2. Rectangle-shaped etch pits are observed for the first time on the (100) oriented epilayers of this material. The growth
temperature and Hgl2 pressure used for the growth experiments have significant effects on the layer morphology and composition. 相似文献
6.
非掺杂p型MBE—Hg1—xCdxTe材料的受主性质 总被引:4,自引:0,他引:4
对经250℃P型热处理获得的Hg1-xCdxTeMBE材料进行变温霍耳测量和理论拟合计算,由此得到HgCdTe-MBE材料的受主浓度为2-3×10^16cm^-3,残余施主浓度为5×10^15cm^-3左右,两才相比显示材料的补偿度较低,拟合得到的汞空位受主能级为15-18meVdisplay structure 相似文献
7.
8.
The determination of cut-off wavelength, λ
co, and composition distribution for Hg1-xCdxTe has been discussed in this paper. A shift of the cut-off wavelength was found from the photo-response calculation for the
HgCdTe devices with the same energy gap Eg but different thickness d. An expression of λ
co(x,T,d) has been derived from the half-maximum photo-response curve calculation. The composition uniformity has been determined
from the room-temperature transmission fitting procedure. The composition real space distribution is suggested to be determined
by the combination of absorption edge phenomenon and thermal imaging technique. 相似文献
9.
碲镉汞液相外延薄膜生长技术与性能 总被引:1,自引:0,他引:1
用液相外延的方法在CdZnTe衬底上生长Hg1-xCdxTe材料,获得了表面形貌好,位错密度低,组份均匀的碲匐汞外延材料,生长工艺对材料的参数控制有较好重复性,外延材料经热处理后,材料的P型和N型电学参数都达到较好的水平,并具有良好的可重复性。 相似文献
10.
A model is presented which describes the motion of and interactions among some of the native point defects and foreign impurities
in Hg1-xCdxTe. Semi-quantitative simulations of typical process problems are performed for cases where only Hg interstitials, Hg vacancies,
and cation impurities are important. Results for the formation of n-on-p junctions by the Hg anneal of high vacancy concentration
material, indicate that junction depths may be a significant function of the n-type dopant concentration. For the case where
low vacancy, n-type material is annealed in a Hg-poor ambient, simulation results confirm the difficulty in forming a high
quality, well-defined p-on-n junction. This difficulty arises because of the generation of Hg vacancy/interstitial pairs throughout
the bulk during most of the process. It is demonstrated that impurity gettering can be described by our modeling approach.
All simulation results attempted to date are consistent with the available experimental data. 相似文献
11.
The Hg0.8Cd0.2Te type-conversion, Hg self-diffusion and interdiffusion processes are analyzed in the context of a first order reaction kinetics
approach. Sets of nonlinear, stiffly coupled continuity equations are presented which describe the underlying physics, and
their solutions model the observed macroscopic behavior. It is demonstrated that the Frenkel pair mechanism interactions dominated
by the cation sublattice, in conjunction with basic diffusive and drift properties of the ionized point defects, comprise
the basic processes which effect all macroscopic phenomena discussed. Existing experimental results are reviewed and apparent
discrepancies discussed. Use is made of the Stanford University mercury cadmium telluride process simulator to provide quantitative
and insightful examples of important results. 相似文献
12.
空间用1.6μmHg1—xCdxTe室温光伏探测器 总被引:3,自引:0,他引:3
报道敢采用改进的区熔工艺生长的三元系金属化合物半导体HgCdTe材料研制的短波光伏探测器,其工作温度为室温,在响应波段1.58-1.64μm内探测率优于3.0×10^-11cmHz^1/2W^-1,量子效率达70%。暗电流主要受制于扩散电流与产生复合电流,器件经环境模拟试验,定标与联试,完全符合空间工程应用的要求。 相似文献
13.
A. I. D'Souza R. E. Dewames P. S. Wijewarnasuriya G. Hildebrandt J. M. Arias 《Journal of Electronic Materials》2001,30(6):585-589
VLWIR (c∼15 m to 17 m at 78 K) detectors have been characterized as a function of temperature to determine the dominant current mechanisms
impacting detector performance. Id−Vd curves indicate that VLWIR detectors are diffusion limited in reverse and near zero bias voltages down to temperatures in
the 40 K range. At 30 K the detectors are limited by tunneling currents in reverse bias. Since the detectors are diffusion
limited near zero bias down to 40 K, the R0Aimp versus temperature data represents the diffusion current performance of the detector as a function of temperature. The detector
spectral response measurement and active layer thickness are utilized to calculate the HgCdTe layer x value and the optical
activation energy Ea optical. The activation energy, Ea electrical, obtained from the measured diffusion limited R0Aimp versus temperature data is not equal to the activation energy, Ea optical, obtained from the spectral response measurement for all x values measured. Ea electrical=*Ea optical, where ranges between 0.64 and 1.0 For cutoff wavelengths in the 9 m at 78 K, Ea electrical=Ea optical. Ea electrical=0.65* Ea optical have been measured forc=17 m at 78 K detectors. As the band gap energy decreases to values in the range of 70 meV and lower, it is reasonable to
expect a more dominant role of band tailing effects on the transport properties of the material system. In such a picture,
one would expect the optical band gap to be unmodified, whereas the intrinsic concentration could be enhanced from its value
for the ideal semiconductor. Such a picture could explain the observed behavior. Further probing experiments and modeling
efforts will help clarify the physics of this behavior. 相似文献
14.
Independently accessed back-to-back HgCdTe photodiodes: A new dual-band infrared detector 总被引:3,自引:0,他引:3
M. B. Reine P. W. Norton R. Starr M. H. Weiler M. Kestigian B. L. Musicant P. Mitra T. Schimert F. C. Case Lb. Bhat H. Ehsani V. Rao 《Journal of Electronic Materials》1995,24(5):669-679
We report the first data for a new two-color HgCdTe infrared detector for use in large dual-band infrared focal plane arrays
(IRFPAs). Referred to as the independently accessed back-to-back photodiode structure, this novel dual-band HgCdTe detector
provides independent electrical access to each of two spatially collocated back-to-back HgCdTe photodiodes so that true simultaneous
and independent detection of medium wavelength (MW, 3–5 μm) and long wavelength (LW, 8–12 μm) infrared radiation can be accomplished.
This new dual-band detector is directly compatible with standard backside-illuminated bump-interconnected hybrid HgCdTe IRFPA
technology. It is capable of high fill factor, and allows high quantum efficiency and BLIP sensitivity to be realized in both
the MW and LW photodiodes. We report data that demonstrate experimentally the key features of this new dual-band detector.
These arrays have a unit cell size of 100 x 100 μm2, and were fabricated from a four-layer p-n-N-P HgCdTe film grown in situ by metalorganic chemical vapor deposition on a CdZnTe
substrate. At 80K, the MW detector cutoff wavelength is 4.5 μm and the LW detector cutoff wavelength is 8.0 μm. Spectral crosstalk
is less than 3%. Data confirm that the MW and LW photodiodes are electrically and radiometrically independent. 相似文献
15.
用倒易二维点阵对HgCdTe光伏探测器钝化及其热处理行为进行了研究,发现测射沉积的钝化膜会引起HgCdTe的晶面弯曲,严重的会出现晶面扭曲和mosaic结构,而钝化后的热处理能改善MCT晶体的完整性,在不同的钝化介质层钝化MCT的研究中发现,ZnS钝化层在高温下并不稳定,而CdTe钝化层却能保持较高的耐温性能。 相似文献
16.
Molecular beam epitaxy HgCdTe growth-induced void defects and their effect on infrared photodiodes 总被引:3,自引:0,他引:3
J. M. Arias M. Zandian J. Bajaj J. G. Pasko L. O. Bubulac S. H. Shin R. E. De Wames 《Journal of Electronic Materials》1995,24(5):521-524
We have carried out a study and identified that MBE HgCdTe growth-induced void defects are detrimental to long wavelength
infrared photodiode performance. These defects were induced during nucleation by having surface growth conditions deficient
in Hg. Precise control and reproducibility of the CdZnTe surface temperature and beam fluxes are required to minimize such
defects. Device quality material with void defect concentration values in the low 102 cm2 range were demonstrated. 相似文献
17.
Effect of dislocations on performance of LWIR HgCdTe photodiodes 总被引:2,自引:0,他引:2
The epitaxial growth of HgCdTe on alternative substrates has emerged as an enabling technology for the fabrication of large-area
infrared (IR) focal plane arrays (FPAs). One key technical issue is high dislocation densities in HgCdTe epilayers grown on
alternative substrates. This is particularly important with regards to the growth of HgCdTe on heteroepitaxial Si-based substrates,
which have a higher dislocation density than the bulk CdZnTe substrates typically used for epitaxial HgCdTe material growth.
In the paper a simple model of dislocations as cylindrical regions confined by surfaces with definite surface recombination
is proposed. Both radius of dislocations and its surface recombination velocity are determined by comparison of theoretical
predictions with carrier lifetime experimental data described by other authors. It is observed that the carrier lifetime depends
strongly on recombination velocity; whereas the dependence of the carrier lifetime on dislocation core radius is weaker. The
minority carrier lifetime is approximately inversely proportional to the dislocation density for densities higher than 105 cm−2. Below this value, the minority carrier lifetime does not change with dislocation density. The influence of dislocation density
on the R0A product of long wavelength infrared (LWIR) HgCdTe photodiodes is also discussed. It is also shown that parameters of dislocations
have a strong effect on the R0A product at temperature around 77 K in the range of dislocation density above 106 cm−2. The quantum efficiency is not a strong function of dislocation density. 相似文献
18.
J. M. Arias J. G. Pasko M. Zandian S. H. Shin G. M. Williams L. O. Bubulac R. E. De Wames W. E. Tennant 《Journal of Electronic Materials》1993,22(8):1049-1053
We recently succeeded in fabricating planar Hg1−yCdyTe/Hg1−xCdxTe (x<y) heterostructure photodiodes with the p-on-n configuration. Here we discuss early results in detail and present new
results on an expanded range of infrared operation. The material used for this demonstration was grown by molecular beam epitaxy
on lattice-matched CdZnTe substrates. The p-on-n planar devices consist of an arsenic-doped p-type epilayer (y∼0.28) atop
a long wavelength infrared n-type epilayer (x=0.22–0.23). The planar junctions were formed by selective pocket diffusion of
arsenic deposited on the surface by ion implantation. Detailed analysis of the current-voltage characteristics of these diodes
as a function of temperature shows that they have high performance and that their dark currents are diffusion-limited down
to 52K. Low frequency noise measurements at a reverse bias voltage of 50 mV resulted in noise current values (at 1 Hz) as
low as 1×10−14 amps/Hz0.5 at 77K. Average RoA values greater than 106 Ω-cm2 at 40K were obtained for these devices with cut-off wavelength values in the 10.6 to 12 μm range. Seventy percent of these
devices have RoA values greater than 105 Ω-cm2 at 40K; further studies are needed to improve device uniformity. These results represent the first demonstration that high
performance long wavelength infrared devices operating at 40K can be made using HgCdTe material grown by a vapor phase epitaxy
growth technique. 相似文献
19.
Hg1-xCdxTe光伏探测器的表面漏电流机制及其钝化 总被引:2,自引:0,他引:2
表面漏电流能对Hg1-xCdxTe光伏探测器性能产生很大的影响,因此选择合适的钝化工艺尤其重要。本文主要论述了Hg1-xCdxTe光伏探测器表面漏电流机制及其钝化技术的发展状况。 相似文献
20.
V. Natarajan N. R. Taskar I. B. Bhat S. K. Ghandhi 《Journal of Electronic Materials》1988,17(6):479-483
The organometallic vapor phase epitaxy of HgCdTe onto (100)2°-(110) GaAs substrates is described in this paper. A buffer layer
of CdTe has been grown prior to the growth of HgCdTe, to take up the large lattice mismatch with the GaAs. Considerations
for the thickness of this buffer layer are outlined, and it is shown by quantitative Secondary Ion Mass Spectroscopy that
there is negligible diffusion of gallium from the GaAs substrate for the growth conditions described. Hall effect measurements
give mobilities comparable to those reported for bulk grown crystals. An extrinsicn-type carrier concentration of 2 × 1016/cm3 is obtained, and is mainly due to residual impurities in the starting chemicals. The alloy composition has been determined
at 298 K by Fourier transform infrared transmission (FTIR) spectrometry; this is found to be extremely uniform over a 15 ×
7 mm area, as evidenced by an overlapping of FTIR plots taken over this area. HgCdTe layers have been grown on buffer layers
varying in thickness from 0.1 to 1.9μm. It is found that a buffer thickness of about 1.9μm or larger is required to obtain high quality HgCdTe, both in terms of the electrical characteristics (mobility and carrier
concentration) and the infrared transmission curves (peak transmission). 相似文献