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1.
R. Pal A. Malik V. Srivastav B. L. Sharma V. Dhar B. Sreedhar H. P. Vyas 《Journal of Electronic Materials》2006,35(10):1793-1800
A compositionally graded CdTe-Hg1−xCdxTe interface was created by deposition of CdTe on p-HgCdTe and subsequent annealing. The compositionally graded layer between
CdTe and HgCdTe was formed by an interdiffusion process and was used for passivation. The composition gradient (Δx) in the
interfacial region and the width of the graded region were tailored by adopting a suitable annealing procedure. The effect
of process conditions on the interfacial profile and photoelectric properties such as lifetime and surface recombination velocity
was studied in detail. Surface recombination velocity of the p-HgCdTe could be reduced to the level of 3,000 cm/s at 77 K,
which represents very good passivation characteristics. The passivation layer formed by this method can be used for the fabrication
of high performance and stable modern infrared detectors. Thus, a passivation process is developed, which is simple, effective,
reproducible, and compatible with the HgCdTe device fabrication and packaging processes. 相似文献
2.
3.
Bake stability of long-wavelength infrared HgCdTe photodiodes 总被引:2,自引:0,他引:2
A. Mestechkin D. L. Lee B. T. Cunningham B. D. Mac Leod 《Journal of Electronic Materials》1995,24(9):1183-1187
The bake stability was examined for HgCdTe wafers and photodiodes with CdTe surface passivation deposited by thermal evaporation.
Electrical and electrooptical measurements were performed on various long-wavelength infrared HgCdTe photodiodes prior to
and after a ten-day vacuum bakeout at 80°C, similar to conditions used for preparation of tactical dewar assemblies. It was
found that the bakeout process generated additional defects at the CdTe/ HgCdTe interface and degraded photodiode parameters
such as zero bias impedance, dark current, and photocurrent. Annealing at 220°C under a Hg vapor pressure following the CdTe
deposition suppressed the interface defect generation process during bakeout and stabilized HgCdTe photodiode performance. 相似文献
4.
不同钝化结构的HgCdTe光伏探测器暗电流机制 总被引:7,自引:0,他引:7
在同一HgCdTe晶片上制备了单层ZnS钝化和双层(CdTe+ZnS)钝化的两种光伏探测器,对器件的性能进行了测试,发现双层钝化的器件具有较好的性能.通过理论计算,分析了器件的暗电流机制,发现单层钝化具有较高的表面隧道电流.通过高分辨X射线衍射中的倒易点阵技术研究了单双层钝化对HgCdTe外延层晶格完整性的影响,发现单层ZnS钝化的HgCdTe外延层产生了大量缺陷,而这些缺陷正是单层钝化器件具有较高表面隧道电流的原因. 相似文献
5.
Changzhen Wang Steve Tobin Themis Parodos David J. Smith 《Journal of Electronic Materials》2006,35(6):1192-1196
The microstructure of p-n device structures grown by liquid-phase epitaxy (LPE) on CdZnTe substrates has been evaluated using
transmission electron microscopy (TEM). The devices consisted of thick (∼21-μm) n-type layers and thin (∼1.6-μm) p-type layers,
with final CdTe (∼0.5 μm) passivation layers. Initial observations revealed small defects, both within the n-type layer (doped
with 8×1014/cm3 of In) and also within the p-type layer but at a much reduced level. These defects were not visible, however, in cross-sectional
samples prepared by ion milling with the sample held at liquid nitrogen temperature. Only isolated growth defects were observed
in samples having low indium doping levels (2×1014/cm3). The CdTe passivation layers were generally columnar and polycrystalline, and interfaces with the p-type HgCdTe layers were
uneven. No obvious structural changes were apparent in the region of the CdTe/HgCdTe interfaces as a result of annealing at
250°C. 相似文献
6.
We assessed p-n junction depth and stress in HgCdTe implanted with various ion species. After post-implantation annealing,
junction depth was measured using a differential Hall measurement. The stress induced by implantation was determined by measuring
wafer curvature or using Raman spectroscopy. Samples with B or Mg implantation had p-n junctions that were three to five times
deeper than samples with Ca, Cd, or Hg implantation. The implantation of elements with a small ionic radius, such as B or
Mg, leads to compressive stress in implantation layers. In contrast, the implantation of Ca, Cd, or Hg, which are ions with
a radius similar to that of Hg cations, leads to a comparatively high tensile stress in the layers. The results indicate that
the stress is caused by a change in volume when the implanted ions substitute the Hg sublattice and by an increase in volume
caused by the generation of vacancies and interstistials. These results suggest that implantation-induced stress is an important
factor influencing the depth of p-n junctions. 相似文献
7.
采用CdTe/ZnS复合钝化技术对长波HgCdTe薄膜进行表面钝化,并对钝化膜生长工艺进行了改进。采用不同钝化工艺分别制备了MIS器件和二极管器件,并进行了SEM、C-V和I-V表征分析,研究了HgCdTe/钝化层之间的界面特性及其对器件性能的影响。结果表明,钝化工艺改进后所生长的CdTe薄膜更为致密且无大的孔洞,CdTe/HgCdTe界面晶格结构有序度获得改善;采用改进的钝化工艺制备的MIS器件C-V测试曲线呈现高频特性,界面固定电荷面密度从改进前的1.671011 cm-2下降至5.691010 cm-2;采用常规钝化工艺制备的二极管器件在较高反向偏压下出现较大的表面沟道漏电流,新工艺制备的器件表面漏电现象获得了有效抑制。 相似文献
8.
CdTe钝化的HgCdTe非平衡载流子表面复合速度的实验研究 总被引:2,自引:2,他引:0
利用Ar^+束央求宙积技术在GgCdTe表面实现了低温CdTe介质薄膜的低温生长。在用-HgCdTe晶片表面分别用CdTe介质膜、HgCdTe自身阳极氧化膜进行表面钝化。利用光电导衰退测量技术测量了两种不同表面钝化的薄HgCdTe晶片的非平衡载流子(少数载流子)寿命,并通过光电导衰减信号波形的拟合,得到两种不同表面钝化的HgCdTe表面复合速度。实验结果表明,获得的CdTe/HgCdTe界面质量已 相似文献
9.
多层HgCdTe异质外延材料的热退火应力分析 总被引:1,自引:0,他引:1
前期研究采用高温热处理方法,获得了抑制位错的最佳退火条件.通过比对实验,发现不同衬底上HgCdTe表面的CdTe钝化层在热处理过程中对位错的抑制作用各有不同.结合晶格失配应力和热应力对不同异质结构进行理论计算,借助X射线摇摆曲线的倒易空间分析,解释了CdTe钝化层对HgCdTe位错抑制的影响作用. 相似文献
10.
11.
J. Zhang G. K. O. Tsen J. Antoszewski J. M. Dell L. Faraone W. D. Hu 《Journal of Electronic Materials》2010,39(7):1019-1022
In order to evaluate the effectiveness of CdTe surface passivating layers, HgCdTe photoconductors with and without CdTe sidewall
passivation were fabricated. As expected, photoconductors with CdTe sidewall passivation demonstrated significantly higher
responsivity in comparison with those without sidewall passivation, indicating the effectiveness of molecular-beam epitaxially
(MBE)-grown CdTe as a passivation layer in reducing surface recombination velocity. Characterization of the responsivity differences
between photoconductors with and without sidewall CdTe passivation offers a potential method for measuring the interface/surface
recombination velocity. This has been demonstrated in this paper by extracting the value of the surface recombination velocity
using the Synopsys Sentaurus commercial modeling package to fit experimental responsivity data for fully and partially passivated
devices. 相似文献
12.
C. F. Wan J. D. Luttmer R. S. List R. L. Strong 《Journal of Electronic Materials》1995,24(9):1293-1297
Piezoelectric effect in long-wavelength infrared (LWIR) HgCdTe has been studied using metal-insulator-semiconductor (MIS)
and p-n homojunction devices. A cantilever beam technique was used to measure the shift in flatband voltage in the MIS devices
as a function of applied strain, from which piezoelectric constant was derived. This is the first time such a value has been
reported in the literature. Subsequent calculation showed that the thermal stress from cryogenic cool (from 300 to 77K) of
hybridized infrared devices fabricated on (111) HgCdTe surfaces induced a piezoelectric field of∼1840 V/cm. This field is
present in the space charge regions in the semiconductor where there is no free carrier. It reinforces the built-field in
an n-on-p diode fabricated on the (111)A HgCdTe surface. Thus, the diode is more prone to the thermal stress than one fabricated
on the (lll)B surface. Electrical measurement of reverse-bias dark currents in HgCdTe photodiodes under applied compressive
and tensile stress confirmed the existence of a strain-induced field in the junction. 相似文献
13.
Characterization of CdTe for HgCdTe surface passivation 总被引:2,自引:0,他引:2
L. O. Bubulac W. E. Tennant J. Bajaj J. Sheng R. Brigham A. H. B. Vanderwyck M. Zandian W. V. Mc Levige 《Journal of Electronic Materials》1995,24(9):1175-1182
The objectives of this work are to study the physical and chemical structure of CdTe films using secondary ion mass spectrometry
(SIMS) and atomic force miroscopy (AFM) and to demonstrate the usefulness of these analytical techniques in determining the
characteristics of CdTe-passivation films deposited by different techniques on HgCdTe material. Three key aspects of CdTe
passivation of HgCdTe are addressed by different analytical tools: a) morphological microstructure of CdTe films examined
by atomic force microscopy; b) compositional profile across the interface determined by Matrix (Te)—SIMS technique; c) concentration
of various impurities across the CdTe/HgCdTe structure profiled by secondary ion-mass spectrometry. 相似文献
14.
Sneha Banerjee Peng-Yu Su Rajendra Dahal Ishwara B. Bhat Jeremy D. Bergeson Caleb Blissett Fikri Aqariden Bengi Hanyaloglu 《Journal of Electronic Materials》2014,43(8):3012-3017
CdTe passivation films have been deposited on Hg1?x Cd x Te (x = 0.35) samples used for infrared detectors by low-pressure chemical vapor deposition (LPCVD) and atomic layer deposition (ALD) at temperatures as low as 135°C to 170°C. ALD has been used to deposit an initially uniform starting surface before continuing the deposition using LPCVD. Favorable conformal coverage has been demonstrated on high-aspect-ratio HgCdTe structures. LPCVD deposition rates of 40 nm/h to 70 nm/h were obtained by varying the sample temperature from 135°C to 170°C. Lifetime measurements carried out at 300 K exhibited a significant improvement in minority-carrier lifetime from 0.9 μs (sample without passivation) to 4.28 μs for samples passivated at 135°C. 相似文献
15.
碲镉汞物理与化学钝化界面的AES研究 总被引:1,自引:1,他引:0
采用化学和物理方法分别在Hg1-xCdxTe (MCT)表面制备了阳极氟化膜、CdTe、ZnS和类金刚石薄膜(DLC)钝化层.采用俄歇光谱(AES)和红外透射光谱(IR)研究了这些钝化层与MCT之间的界面特性.结果表明与阳极氟化膜和CdTe膜相比,ZnS和DLC膜能较好地抑制MCT组元的外扩散.ZnS层中的Zn和S 易于向MCT内部扩散,而且发现在ZnS层中有O的存在,这可能是由于ZnS易与空气中水份发生作用所致.而DLC中C向MCT内表面扩散较少.MCT表面沉积DLC薄膜后红外透过率较ZnS有明显的提高. 相似文献
16.
Y. Nemirovsky N. Amir D. Goren G. Asa N. Mainzer E. Weiss 《Journal of Electronic Materials》1995,24(9):1161-1168
The metalorganic chemical vapor deposition (MOCVD) growth of CdTe on bulk n-type HgCdTe is reported and the resulting interfaces
are investigated. Metalinsulator-semiconductor test structures are processed and their electrical properties are measured
by capacitance-voltage and current-voltage characteristics. The MOCVD CdTe which was developed in this study, exhibits excellent
dielectric, insulating, and mechano-chemical properties as well as interface properties, as exhibited by MIS devices where
the MOCVD CdTe is the single insulator. Interfaces characterized by slight accumulation and a small or negligible hysteresis,
are demonstrated. The passivation properties of CdTe/ HgCdTe heterostructures are predicted by modeling the band diagram of
abrupt and graded P-CdTe/n-HgCdTe heterostructures. The analysis includes the effect of valence band offset and interface
charges on the surface potentials at abrupt hetero-interface, for typical doping levels of the n-type layers and the MOCVD
grown CdTe. In the case of graded heterojunctions, the effect of grading on the band diagram for various doping levels is
studied, while taking into consideration a generally accepted valence band offset. The MOCVD CdTe with additional pre and
post treatments and anneal form the basis of a photodiode with a new design. The new device architecture is based on a combination
of a p-on-n homojunction in a single layer of n-type HgCdTe and the CdTe/HgCdTe heterostructure for passivation. 相似文献
17.
J. K. White J. Antoszewski R. Pal C. A. Musca J. M. Dell L. Faraone J. Piotrowski 《Journal of Electronic Materials》2002,31(7):743-748
The formation of n-on-p junctions by reactive ion etching (RIE) of HgCdTe using an H2/CH4 plasma has previously been demonstrated to produce high-performance photodiodes. To fully exploit the inherent advantages
of this process, a compatible surface-passivation technology that provides long-term stability is required. This paper examines
the effects of thermally evaporated CdTe- and ZnS-passivation on RIE-formed photodiodes undergoing low-temperature baking
in a vacuum at temperatures typically used for Dewar bakeout. Experimental results show that as a single passivation layer,
neither CdTe nor ZnS are suitable for vacuum packaging of RIE-formed diodes that are to be operated at cryogenic temperatures.
A double passivation layer, however, consisting of CdTe passivation and an insulating overlayer of ZnS, produces photodiodes
that are stable throughout 175 h, approximately 1 week, of 80°C baking in a vacuum. 相似文献
18.
P. Boieriu C. Buurma R. Bommena C. Blissett C. Grein S. Sivananthan 《Journal of Electronic Materials》2013,42(12):3379-3384
Bulk passivation of semiconductors with hydrogen continues to be investigated for its potential to improve device performance. In this work, hydrogen-only inductively coupled plasma (ICP) was used to incorporate hydrogen into long-wavelength infrared HgCdTe photodiodes grown by molecular-beam epitaxy. Fully fabricated devices exposed to ICP showed statistically significant increases in zero-bias impedance values, improved uniformity, and decreased dark currents. HgCdTe photodiodes on Si substrates passivated with amorphous ZnS exhibited reductions in shunt currents, whereas devices on CdZnTe substrates passivated with polycrystalline CdTe exhibited reduced surface leakage, suggesting that hydrogen passivates defects in bulk HgCdTe and in CdTe. 相似文献
19.
V. Kumar R. Pal P. K. Chaudhury B. L. Sharma V. Gopal 《Journal of Electronic Materials》2005,34(9):1225-1229
Passivant-Hg1−xCdxTe interface has been studied for the CdTe and anodic oxide (AO) passivants. The former passivation process yields five times
lower surface recombination velocity than the latter process. Temperature dependence of surface recombination velocity of
the CdTe/n-HgCdTe and AO/n-HgCdTe interface is analyzed. Activation energy of the surface traps for CdTe and AO-passivated
wafers are estimated to be in the range of 7–10 meV. These levels are understood to be arising from Hg vacancies at the HgCdTe
surface. Fixed charge density for CdTe/n-HgCdTe interface measured by CV technique is 5×1010 cm−2, which is comparable to the epitaxially grown CdTe films. An order of magnitude improvement in responsivity and a factor
of 4 increase in specific detectivity (D*) is achieved by CdTe passivation over AO passivation. This study has been conducted
on photoconductive detectors to qualify the CdTe passivation process, with an ultimate aim to use it for the passivation of
p-on-n and n-on-p HgCdTe photodiodes. 相似文献
20.
V. Ariel V. Garber D. Rosenfeld G. Bahir V. Richter N. Mainzer A. Sher 《Journal of Electronic Materials》1995,24(9):1169-1174
In this study, CdTe epilayers were grown by metalorganic chemical vapor deposition on epitaxial HgCdTe with the purpose of
developing suitable passivation for HgCdTe photodiodes. Two types of CdTe layers were investigated. One was grown directly,in situ, immediately following the growth of HgCdTe. The second type of CdTe was grown indirectly, on top of previously grown epitaxial
HgCdTe samples. In this case, the surface of the HgCdTe was exposed to ambient atmosphere, and a surface cleaning procedure
was applied. The material and structural properties of the CdTe/HgCdTe interfaces were investigated using secondary ion mass
spectroscopy, Auger electron spectroscopy, Rutherford back scattering, and x-ray double crystal diffractometry techniques.
Electrical properties of the CdTe/HgCdTe heterostructure were determined by capacitance-voltage (C-V) characterization of
Schottky barrier devices and metal insulator semiconductor devices. Also, a preliminary current-voltage characterization of
n+ p photodiodes was performed. A theoretical model suitable for analysis of graded heterojunction devices was used for interpretation
of C-V measurements. 相似文献