共查询到20条相似文献,搜索用时 31 毫秒
1.
CdTe epilayers are grown by metalorganic chemical vapor deposition (MOCVD) on bulk HgCdTe crystals with x ~ 0.22 grown by
the traveling heater method (THM). The THM HgCdTe substrates are (111) oriented and the CdTe is grown on the Te face. The
metalorganic sources are DMCd and DETe, and the growth is performed at subatmospheric pressure. Ultraviolet (UV) photon-assisted
hydrogen radicals pretreatment plays a dominant role in the electrical properties of the resulting heterostructures. The requirements
of a good passivation for HgCdTe photodiodes vis-a-vis the passivation features of CdTe/HgCdTe heterostructures are discussed.
The effect of valence band offset and interface charges on the band diagrams of p-isotype CdTe/HgCdTe heterostructures, for
typical doping levels of the bulk HgCdTe substrates and the MOCVD grown CdTe, is presented. Electrical properties of the CdTe/HgCdTe
passivation are determined by capacitance-voltage and current-voltage characteristics of metal-insulator-semiconductor test
devices, where the MOCVD CdTe is the insulator. It is found that the HgCdTe surface is strongly inverted and the interface
charge density is of the order of 1012cm2 when the CdTe epilayer is grown without the UV pretreatment. With the in-situ UV photon-assisted hydrogen radicals pretreatment,
the HgCdTe surface is accumulated and the interface charge density is -4. 1011 cm-2. 相似文献
2.
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
3.
4.
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
5.
Heteroepitaxy of HgCdTe(112) infrared detector structures on Si(112) substrates by molecular-beam epitaxy 总被引:4,自引:0,他引:4
T. J. De Lyon R. D. Rajavel J. E. Jensen O. K. Wu S. M. Johnson C. A. Cockrum G. M. Venzor 《Journal of Electronic Materials》1996,25(8):1341-1346
High-quality, single-crystal epitaxial films of CdTe(112)B and HgCdTe(112)B have been grown directly on Si(112) substrates
without the need for GaAs interfacial layers. The CdTe and HgCdTe films have been characterized with optical microscopy, x-ray
diffraction, wet chemical defect etching, and secondary ion mass spectrometry. HgCdTe/Si infrared detectors have also been
fabricated and tested. The CdTe(112)B films are highly specular, twin-free, and have x-ray rocking curves as narrow as 72
arc-sec and near-surface etch pit density (EPD) of 2 × 106 cm−2 for 8 μm thick films. HgCdTe(112)B films deposited on Si substrates have x-ray rocking curve FWHM as low as 76 arc-sec and
EPD of 3-22 × 106 cm−2. These MBE-grown epitaxial structures have been used to fabricate the first high-performance HgCdTe IR detectors grown directly
on Si without use of an intermediate GaAs buffer layer. HgCdTe/Si infrared detectors have been fabricated with 40% quantum
efficiency and R0A = 1.64 × 104 Ωm2 (0 FOV) for devices with 7.8 μm cutoff wavelength at 78Kto demonstrate the capability of MBE for growth of large-area HgCdTe
arrays on Si. 相似文献
6.
Heteroepitaxy of HgCdTe (211)B on Ge substrates by molecular beam epitaxy for infrared detectors 总被引:3,自引:0,他引:3
J. P. Zanatta P. Ferret G. Theret A. Million M. Wolny J. P. Chamonal G. Destefanis 《Journal of Electronic Materials》1998,27(6):542-545
Epitaxial growth of (211)B CdTe/HgCdTe has been achieved on two inch germanium (Ge) by molecular beam epitaxy (MBE). Germanium
was chosen as an alternative substrate to circumvent the weaknesses of CdZnTe wafers. The ease of surface preparation makes
Ge an attractive candidate among many other alternative substrates. Best MBE CdTe growth results were obtained on (211) Ge
surfaces which were exposed to arsenic and zinc fluxes prior to the MBE growth. This surface preparation enabled CdTe growth
with B-face crystallographic polarity necessary for the HgCdTe growth. This process was reproducible, and produced a smooth
and mirror-like surface morphology. The best value of the {422} x-ray double diffraction full width at half maximum measured
from the HgCdTe layer was 68 arc-s. We present the 486 point maps of FWHM statistical values obtained from CdTe/Ge and HgCdTe/CdTe/Ge.
High resolution microscopy electron transmission and secondary ion mass spectroscopy characterization results are also presented
in this paper. High-performance middle wavelength infrared HgCdTe 32-element photodiode linear arrays, using the standard
LETI/LIR planar n-on-p ion implanted technology, were fabricated on CdTe/Ge substrates. At 78K, photodiodes exhibited very
high R0A figure of merit higher than 106 Ωcm−2 for a cutoff wavelength of 4.8 μm. Excess low frequency noise was not observed below 150K. 相似文献
7.
H. Nishino S. Murakami T. Saito Y. Nishijima H. Takigawa 《Journal of Electronic Materials》1995,24(5):533-537
We studied dislocation etch pit density (EPD) profiles in HgCdTe(lOO) layers grown on GaAs(lOO) by metalorganic chemical vapor
deposition. Dislocation profiles in HgCdTe(lll)B and HgCdTe(lOO) layers differ as follows: Misfit dislocations in HgCdTe(lll)B
layers are concentrated near the HgCdTe/CdTe interfaces because of slip planes parallel to the interfaces. Away from the HgCdTe/CdTe
interface, the HgCdTe(111)B dislocation density remains almost constant. In HgCdTe(lOO) layers, however, the dislocations
propagate monotonically to the surface and the dislocation density decreases gradually as dislocations are incorporated with
increasing HgCdTe(lOO) layer thicknesses. The dislocation reduction was small in HgCdTe(lOO) layers more than 10 μm from the
HgCdTe/CdTe interface. The CdTe(lOO) buffer thickness and dislocation density were similarly related. Since dislocations glide
to accommodate the lattice distortion and this movement increases the probability of dislocation incorporation, incorporation
proceeds in limited regions from each interface where the lattice distortion and strain are sufficient. We obtained the minimum
EPD in HgCdTe(100) of 1 to 3 x 106 cm-2 by growing both the epitaxial layers more than 8 μm thick. 相似文献
8.
A. I. D’Souza J. Bajaj R. E. De Wames D. D. Edwall P. S. Wijewarnasuriya N. Nayar 《Journal of Electronic Materials》1998,27(6):727-732
Mid wavelength infrared p-on-n double layer planar heterostructure (DLPH) photodiodes have been fabricated in HgCdTe double
layers grown in situ by liquid phase epitaxy (LPE), on CdZnTe and for the first time on CdTe/sapphire (PACE-1). Characterization of these devices
shed light on the nature of the material limits on device performance for devices performing near theoretical limits. LPE
double layers on CdZnTe and on PACE-1 substrates were grown in a horizontal slider furnace. All the photodiodes are p-on-n
heterostructures with indium as the n-type dopant and arsenic the p-type dopant. Incorporation of arsenic is via implantation
followed by an annealing step that was the same for all the devices fabricated. The devices are passivated with MBE CdTe.
Photodiodes have been characterized as a function of temperature. R0Aimp values obtained between 300 and 78K are comparable for the two substrates and are approximately a factor of five below theoretical
values calculated from measured material parameters. The data, for the PACE-1 substrate, indicates diffusion limited performance
down to 110K. Area dependence gives further indications as to the origin of diffusion currents. Comparable R0Aimp for various diode sizes indicates a p-side origin. R0A and optical characteristics for the photodiodes grown on lattice-matched CdZnTe substrates and lattice mismatched PACE-1
are comparable. Howover, differences were observed in the noise characteristics of the photodiodes. Noise was measured on
50 × 50 μm devices held under a 100 mV reverse bias. At 110K, noise spectrum for devices from the two substrates is in the
low 10−15 A/Hz1/2 range. This value reflects the Johnson noise of the room temperature 1010 Ω feedback resistor in the current amplifier that limits the minimum measurable noise. Noise at 1 Hz, −100 mV and 120K for
the 4.95 μm PACE-1 devices is in the 1–2 × 10−14 A/Hz1/2, a factor of 5–10 lower than previously grown typical PACE-1 n+-on-p layers. Noise at 120K for the 4.60 μm PACE-1 and LPE on CdZnTe was again below the measurement technique limit. Greatest
distinction in the noise characteristics for the different substrates was observed at 163K. No excess low frequency noise
was observed for devices fabricated on layers grown by LPE on lattice-matched CdZnTe substrates. Photodiode noise measured
at 1Hz, −100 mV and 163K in the 4.60 μm PACE-1 layer is in the 1–2×10−13 A/Hz1/2, again a factor of 5–10 lower than previously grown PACE-1 n+-on-p layers. More variation in noise (4×10−13−2×10−12 A/Hz1/2) was observed for devices in the 4.95 μm PACE-1 layer. DLPH devices fabricated in HgCdTe layers grown by LPE on lattice-matched
CdZnTe and on lattice-mismatched PACE-1 have comparable R0A and quantum efficiency values. The distinguishing feature is that the noise is greater for devices fabricated in the layer
grown on lattice mismatched substrates, suggesting dislocations inherent in lattice mismatched material affects excess low
frequency noise but not zero bias impedance. 相似文献
9.
IntroductionAt present Hg Cd Te is the most widely used variable-gap semiconductor for infrared( IR) photodetectors.Over the years it has successfully fought off majorchallenges from extrinsic silicon and lead- tin telluridedevices despite that it has more competitors todaythan ever before.These include Schottky barriers onsilicon,Si Ge heterojunctions,Al Ga As multiplequantum wells,Ga In Sb strained layer superlattices,high temperature superconductors and especially twotypes of thermal … 相似文献
10.
In this paper standard techniques for characterization of HgCdTe liquid phase epitaxial layers (LPE) were presented. The performance of long wavelength p-on-n HgCdTe photodiodes fabricated by arsenic diffusion was described. The correlation between LPE HgCdTe material parameters and properties of the infrared photodiodes was demonstrated. 相似文献
11.
Li He Xiangliang Fu Qingzhu Wei Weiqiang Wang Lu Chen Yan Wu Xiaoning Hu Jianrong Yang Qinyao Zhang Ruijun Ding Xiaoshuang Chen Wei Lu 《Journal of Electronic Materials》2008,37(9):1189-1199
Results of first-principles calculations and experiments focusing on molecular beam epitaxy (MBE) growth of HgCdTe on the
alternative substrates of GaAs and Si are described. The As passivation on (2 × 1) reconstructed (211) Si and its effects
on the surface polarity of ZnTe or CdTe were clarified by examining the bonding configurations of As. The quality of HgCdTe
grown on Si was confirmed to be similar to that grown on GaAs. Typical surface defects in HgCdTe and CdTe were classified.
Good results for uniformities of full width at half maximum (FWHM) values of x-ray rocking curves, surface defects, and x values of Hg1−x
Cd
x
Te were obtained by refining the demanding parameters and possible tradeoffs. The sticking coefficient of As4 for MBE HgCdTe was determined. The effects of Hg-assisted annealing for As activation were investigated experimentally and
theoretically by examining the difference of the formation energy of AsHg and AsTe. Results of focal-plane arrays (FPAs) fabricated with HgCdTe grown on Si and on GaAs are discussed. 相似文献
12.
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
13.
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
14.
P. Mitra S. L. Barnes F. C. Case M. B. Reine P. O’Dette R. Starr A. Hairston K. Kühler M. H. Weiler B. L. Musicant 《Journal of Electronic Materials》1997,26(6):482-487
We report the implementation of recent advances in metalorganic chemical vapor deposition (MOCVD) for in situ growth of four-layer HgCdTe mid wave/ long wave (MW/LW) simultaneous dual-band 64 × 64 infrared detector arrays. This independently
accessed, simultaneous, double-heterojunction p-n-N-P dualband detector has two back-to-back stacked photodiodes grown on
CdZnTe (100) substrates. The LW photodiode is a p-on-n heterojunction grown on top of an MW N-on-P heterojunction photodiode.
Secondary ion mass spectrometry depth profiles of these 28 μ m thick p-n-N-P dual-band films show four well-defined regions
of alloy composition and doping, and agree well with the device design. 64 × 64 arrays of dual-band detectors were fabricated
from these films using electron cyclotron resonance dry etching and CdTe passivation, and hybridized to a dual-band readout
chip. Two bump inter-connects in each unit cell provide independent electrical access to the back-to-back MW and LW photodiodes,
and allow the MW and LW photocurrents to be separate and independent. The dualband infrared focal plane arrays (IRFPAs) spectral
response data at 78K are well-behaved and are fully consistent with that observed in individual singleband LW p-on-n and MW
N-on-P heterojunction devices of the same design. The hybridized 64 × 64 duai-band FPAs have MW and LW average in-band quantum
efficiencies of 79 and 67%, and median D* values of 4.8 × 1011 and 7.1 × 1010 cm-√Hz/W, in the respective spectral bands at 78K. The data demonstrate that MOCVD has progressed significantly toward being
a practical and viable vapor phase in situ growth technology for advanced bandgap-engineered HgCdTe detector arrays. 相似文献
15.
J. K. Markunas L. A. Almeida R. N. Jacobs J. Pellegrino S. B. Qadri N. Mahadik J. Sanghera 《Journal of Electronic Materials》2010,39(6):738-742
Large-area high-quality Hg1–x
Cd
x
Te sensing layers for infrared imaging in the 8 μm to 12 μm spectral region are typically grown on bulk Cd1–x
Zn
x
Te substrates. Alternatively, epitaxial CdTe grown on Si or Ge has been used as a buffer layer for high-quality epitaxial
HgCdTe growth. In this paper, x-ray topographs and rocking-curve full-width at half-maximum (FWHM) data will be presented
for recent high-quality bulk CdZnTe grown by the vertical gradient freeze (VGF) method, previous bulk CdZnTe grown by the
vertical Bridgman technique, epitaxial CdTe buffer layers on Si and Ge, and a HgCdTe layer epitaxially grown on bulk VGF CdZnTe. 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.
T. S. Lee K. K. Choi Y. T. Jeoung H. K. Kim J. M. Kim Y. H. Kim J. M. Chang W. S. Song S. U. Kim M. J. Park S. D. Lee 《Journal of Electronic Materials》1997,26(6):552-555
In this paper, we report the results of capacitance-voltage measurements conducted on several metal-insulator semiconductor (MIS) capacitors in which HgCdTe surfaces are treated with various surface etching and oxidation processes. CdZnTe passivation layers were deposited on HgCdTe surfaces by thermal evaporation after the surfaces were etched with 0.5?2.0% bromine in methanol solution, or thin oxide layers (tox ~ few ten Å) were grown on the surfaces, in order to investigate effects of the surface treatments on the electrical properties of the surfaces, as determined from capacitance-voltage (C-V) measurements at 80K and 1 MHz. A negative flat band voltage has been observed for MIS capacitors fabricated after etching of HgCdTe surfaces with bromine in methanol solutions, which is reported to make the surface Te-rich. It is inferred that residual Te on the surface is a positive charge, Te4+. C-V characteristics for MIS capacitors fabricated on oxide surfaces grown by air-exposure and electrolytic process have shown large hysteresis effects, from which it is inferred that imperfect and electrically active oxide compounds and HgTe particles near the surface become slow interface states. 相似文献
18.
W. Lei R. J. Gu J. Antoszewski J. Dell L. Faraone 《Journal of Electronic Materials》2014,43(8):2788-2794
In this work, GaSb is proposed as a new alternative substrate for the growth of HgCdTe via molecular beam epitaxy (MBE). Due to the smaller mismatch in both lattice constant and coefficient of thermal expansion between GaSb and HgCdTe, GaSb presents a better alternative substrate for the epitaxial growth of HgCdTe, in comparison to alternative substrates such as Si, Ge, and GaAs. In our recent efforts, a CdTe buffer layer technology has been developed on GaSb substrates via MBE. By optimizing the growth conditions (mainly growth temperature and VI/II flux ratio), CdTe buffer layers have been grown on GaSb substrates with material quality comparable to, and slightly better than, CdTe buffer layers grown on GaAs substrates, which is one of the state-of-the-art alternative substrates used in growing HgCdTe for the fabrication of mid-wave infrared detectors. The results presented in this paper indicate the great potential of GaSb to become the next generation alternative substrate for HgCdTe infrared detectors, demonstrating MBE-grown CdTe buffer layers with rocking curve (double crystal x-ray diffraction) full width at half maximum of ~60 arcsec and etch pit density of ~106 cm?2. 相似文献
19.
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
20.
Molecular beam epitaxial HgCdTe material characteristics and device performance: Reproducibility status 总被引:1,自引:0,他引:1
J. Bajaj J. M. Arias M. Zandian J. G. Pasko L. J. Kozlowski R. E. De Wames W. E. Tennant 《Journal of Electronic Materials》1995,24(9):1067-1076
Extensive material, device, and focal plane array (FPA) reproducibility data are presented to demonstrate significant advances
made in the molecular beam epitaxial (MBE) HgCdTe technology. Excellent control of the composition, growth rate, layer thickness,
doping concentration, dislocation density, and transport characteristics has been demonstrated. A change in the bandgap is
readily achieved by adjusting the beam fluxes, demonstrating the flexibility of MBE in responding to the needs of infrared
detection applications in various spectral bands. High performance of photodiodes fabricated on MBE HgCdTe layers reflects
on the overall quality of the grown material. The photodiodes were planar p-on-n junctions fabricated by As ion-implantation
into indium doped, n-type, in situ grown double layer heterostructures. At 77K, diodes fabricated on MBE Hg1−xCdxTe with x ≈ 0.30 (λco
≈ 5.6 μm), x ≈ 0.26 (λco
≈ 7 μm), x ≈ 0.23 (λco ≈ 10 μm) show R0A products in excess of 1 x 106 ohm-cm2, 7 x 105 ohm-cm2, and 3 x 102 ohm-cm2, respectively. These devices also show high quantum efficiency. As a means to assess the uniformity of the MBE HgCdTe material,
two-dimensional 64 x 64 and 128 x 128 mosaic detector arrays were hybridized to Si multiplexers. These focal plane arrays
show an operability as high as 97% at 77K for the x ≈ 0.23 spectral band and 93% at 77K for the x ≈ 0.26 spectral band. The
operability is limited partly by the density of void-type defects that are present in the MBE grown layers and are easily
identified under an optical microscope. 相似文献