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1.
K. Suzuki S. Seto S. Dairaku N. Takojima T. Sawada K. Imai 《Journal of Electronic Materials》1996,25(8):1241-1246
The drift mobilities of chlorine doped high resistivity Cd0.8Zn0.2 Te have been investigated by using the time-of-flight technique. Electron as well as hole mobility in the as-grown crystals
is limited by trap-controlled carrier transport. The energy locations of the defects responsible for carrier trapping are
determined to be Ec- 0.03 and Ev+ 0.14 eV for electrons and holes, respectively. After annealing at 400°C for 80 h, no evidence of trap-controlled mobility
was recognized for electrons. On the other hand, no significant change before and after the annealing was observed for hole
transport. Those results and the change in the photoluminescence spectra before and after the annealing are explained by the
complex defect model composed of the Cd vacancy and chlorine donor. Further, the alloy scattering potentials of ΔUe and ΔUh were estimated by employing the theoretical calculation method recently reported by D. Chattopadhyay [Solid State Commun. 91, 149 (1994)]. 相似文献
2.
Hg1−xCdxTe films were grown by a modified meltetch liquid phase epitaxial (LPE) technique which includes both substrate and epilayer
etchback steps. The crystal quality of epilayer has been investigated by means of transmission electron microscopy, scanning
electron microscopy, and double crystal x-ray diffraction. It has been found that adequate meltetch of the substrate at the
beginning of LPE provides a fresh and flat surface for epitaxial growth, while epilayer meltetch at the end of LPE may prevent
spurious melt sticking. 相似文献
3.
Three indicators (T1000, T5000, and T1000/T5000) are used to appraise the infrared (IR) transmission spectra for Cd1−xZnxTe (CZT) slices. By comparing the values of these three indicators, four typical types of IR spectra are characterized for
CZT crystals. The CZT crystals possessing the four types of IR spectra are different in microstructures, especially the densities
and sizes of Te precipitates, the free carrier concentrations, and the resistivities. Mechanisms for the elimination of tiny
and dense Te precipitates are given by analyzing the variation of the IR transmittance in the range of 500–5000 cm−1 during the annealing process. 相似文献
4.
The low incident angle (surface analysis) and the conventional wide angle (bulk analysis) x-ray diffraction techniques were
employed to investigate the existence of a miscibility gap in the Hg1−xCdxTe system. Samples of initial composition Hg0.46Cd0.54Te were annealed at 140 and 400°C, respectively, for four weeks. The diffraction planes (531) and (642) have been selected
for the x-ray diffraction analysis. The results of this work provide the first, direct experimental evidence for the existence
of a miscibility gap at lower temperature in the Hg1−xCdxTe system. The phase separation occurs primarily in a thin surface layer at 140°C and is reversible after annealing at 530°C.
The compositions of the two compounds at the tie-line at 140°C are Hg0.22Cd0.78Te and Hg0.63Cd0.37Te. 相似文献
5.
Sidney G. Parker 《Journal of Electronic Materials》1976,5(5):497-511
The quality of PbxSn1−xTe crystals to be used in infrared detectors was improved by elimination or reduction in the number of holes, linear voids,
strains and dislocations during growth. This was accomplished by use of stoichiometric or slightly Te-rich charges preheat
treated before use to reduce the number of holes. Linear voids and strains were reduced by using constant diameter growth
tubes of 25 mm diameter. The number of dislocations was reduced by the use of a slow cooling rate and limited contract with
the walls of the growth tube. 相似文献
6.
Hongqiang Lu Malathi Thothathiri Ziming Wu Ishawara Bhat 《Journal of Electronic Materials》1997,26(3):281-284
Indium droplet formation during the epitaxial growth of InxGa1−xN films is a serious problem for achieving high quality films with high indium mole fraction. In this paper, we studied the
formation of indium droplets on the InxGa1−xN films grown by metalorganic chemical vapor deposition (MOCVD) using single crystal x-ray diffraction. It is found that the
indium (101) peak in the x-ray diffraction spectra can be utilized as a quantitative measure to determine the amounts of indium
droplets on the film. It is shown by monitoring the indium diffraction peak that the density of indium droplets increases
at lower growth temperature. To suppress these indium droplets, a modulation growth technique is used. Indium droplet formation
in the modulation growth is investigated and it is revealed in our study that the indium droplets problem has been partially
relieved by the modulation growth technique. 相似文献
7.
The reproducible molecular-beam epitaxy (MBE) growth of dual-band Hg1−xCdxTe (MCT) heterostructures requires routine post-growth wafer analysis for constituent layer thickness and alloy composition,
therefore, demanding nondestructive characterization techniques that offer quick data feedback. This paper reports a multilayer
structure model, which can be least-square fit directly to either Fourier transform infrared (FTIR) transmission or reflection
spectra to provide individual layer thickness, alloy composition, and grading information for various complex structures.
The model, we developed, is based on an accurate representation of both the real and imaginary parts of the MCT dielectric
function across and above E
g
as a function of alloy composition. The parametric, MCT optical-dielectric function for compositions varying between x=0.17
to x=0.5 was developed in the range from 400 cm−1 to 4,000 cm−1, based on a semi-empirical model for the absorption coefficient and extrapolation of the refractive index across E
g
. The model parameters were refined through simultaneous fits to multiple reflection and transmission data sets from as-grown,
double-layer planar heterostructure (DLPH) structures of variable thickness. The multilayer model was tested on a variety
of simple DLPH structures with thick absorber layers (>8 μm) and was compared against traditional FTIR analysis and cross-section
optical microscopy and showed good agreement in both composition and thickness. Model fits to dual-color MCT data and subsequent
analysis of the internal parameter correlation have demonstrated that error bars on absorber layer composition and thickness
could be as low as ∼0.0005 and ∼0.02 μm, correspondingly. 相似文献
8.
Improved Defect and Fourier Transform Infrared Spectroscopy Analysis for Prediction of Yield for HgCdTe Multilayer Heterostructures 总被引:1,自引:0,他引:1
D.D. Lofgreen M.F. Vilela E.P. Smith M.D. Newton D. Beard S.M. Johnson 《Journal of Electronic Materials》2007,36(8):958-962
The ability to accurately predict HgCdTe focal plane array (FPA) performance using nondestructive, postgrowth wafer analysis
is of great importance. These predictions, if accurate, reduce costs by screening the wafers prior to processing, and selecting
only those wafers that are most likely to yield FPAs that meet program specifications. In this paper, we examine the use of
a macrodefect inspection tool, the NSX 1255, from August Technology. This inspection tool has the ability to measure defects
0.5 μm and larger and store the location and size data to a file. We have then, through the use of custom written software, been
able to analyze these data on a wafer by wafer basis. We have also incorporated the use of a thin film transmission matrix
model to analyze room-temperature Fourier transform infrared spectroscopy (FTIR) transmission spectra. This technique, which
is applied to the entire wafer surface, can be used to determine the individual layer thicknesses as well as their compositions.
Then, using analytical expressions for bandgap, absorption, and index of refraction, we can predict responsivity and quantum
efficiency. Through the use of these two inspection tools and our analysis software, we are able to overlay FPA die information
and perform statistics on a die-per-die basis. This allows us to effectively “pass” or “fail” each FPA based on the program
specifications. We are then able to set a minimum criterion for the number of FPAs that pass on any given wafer. That wafer
is then sent off to processing if it meets this criterion. Furthermore, knowing why a wafer fails before it reaches processing
allows for real time feedback to the epilayer growth process. This allows for run-to-run adjustments in order to keep as many
wafers within specifications as possible and increases yield overall.
(Received October 24, 2006; accepted Feburary 26, 2007) 相似文献