X-Ray, Photoluminescence and Etching Studies of Indium-Doped LPE GaAs Layers

1988 ◽  
Vol 144 ◽  
Author(s):  
J.F. Chen ◽  
C. R. Wie ◽  
F. A. Junga
Keyword(s):  
Phase Diagram ◽  
Sharp Increase ◽  
Emission Spectra ◽  
Etch Pit Density ◽  
Double Crystal ◽  
X Ray ◽  
Etch Pit ◽  
In Doping ◽  
Good Crystalline Quality ◽  
Pseudobinary Phase Diagram

ABSTRACTThe effects of In doping on the structural properties of liquid phase epitaxially (LPE) grown GaAs layers are studied. The distribution coefficient of In in the GaAs at 800 ° C was determined to be 0.033 which was consistent with the value calculated from the pseudobinary phase diagram of the ternary system at a dilute In concentration. The full widths at halfmaximum (FWHM) of x-ray double crystal rocking curves show that a GaAs epi-layer of good crystalline quality can be obtained by doping In to a concentration up to 4.3 × 1019 cm−3, beyond which a sharp increase in the FWHM is observed. Etch pit density (EPD) measurement shows that the dislocation density is reduced by doping the epi-layer with In. At the optimal In concentration of 2.4 × 1019 cm−3, the EPD is reduced by a factor of 20 when measured at the surface of a 9 um thick epilayer.Photoluminesce measurements made at 15 K show two sharp emission spectra near the bandedge. The relative intensities of the two emissions, I(l.49eV)/I(l.5eV) are reduced with increasing In content. This suggests that incorporation of Carbon acceptors is suppressed by In doping in the GaAs epilayers. The FWHM as small as 5 meV of the bandedge transition was obtained for the epi-layer doped with In concentration of 2.4 × 1019 cm−3.

Mosaicity and Wafer Bending in SiC Wafers as Measured by Double and Triple Crystal X-Ray Rocking Curve and Peak Position Maps

2007 ◽  
Vol 556-557 ◽  
pp. 213-218 ◽  
Author(s):  
K.W. Kirchner ◽  
Kenneth A. Jones ◽  
Michael A. Derenge ◽  
Michael Dudley ◽  
Adrian R. Powell
Keyword(s):  
Laser Light ◽  
Peak Position ◽  
Etch Pit Density ◽  
Normal Position ◽  
Rocking Curve ◽  
X Ray ◽  
Etch Pit ◽  
Density Map ◽  
Beam Transmission ◽  
Si Wafer

Double and triple crystal rocking curve and peak position maps are constructed for a 4HSiC wafer for the symmetric (0 0 0 8) reflection in the normal position, the same reflection for a sample rotated 90º, and an asymmetric (1 23 6) reflection for the wafer in the normal position. These measurements were corrected for the ‘wobble’ in the instrument by scanning a 4” (1 1 1) Si wafer and assuming that the Si wafer was perfect and attributing the variations in the measurements to instrumental error. The x-ray measurements are correlated with a cross polar image, etch pit density map, white beam transmission x-ray topograph, and a laser light scan.

Growth and characterization of Al–Cu–Li quasicrystals

1988 ◽  
Vol 3 (2) ◽  
pp. 233-237 ◽  
Author(s):  
J. M. Parsey ◽  
H. S. Chen ◽  
A. R. Kortan ◽  
F. A. Thiel ◽  
A. E. Miller ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Alloy System ◽  
Icosahedral Phase ◽  
Solidification Velocity ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Pseudobinary Phase Diagram ◽  
Melt Composition

The alloy system Al–Li–Cu was investigated extensively over the composition range 5.8–8 Al–Cu–3Li to develop a detailed understanding of the formation and properties of the icosahedral phase, known as T2. Material from the various charges was analyzed by optical and electron microscopy, energy dispersive x-ray analysis, differential thermal analysis, and differential scanning calorimetry. The role of the melt composition and the solidification velocity were found to be crucial in determining the micro- and macrostructure and the existence of the icosahedral phase. A pseudobinary phase diagram for the region around Al6CuLi3, is presented based on these analyses. Based on this phase diagram the largest single icosahedral crystals of Al5.1CuLi3 yet reported, with diameters greater than 1 cm, were produced by Bridgman methods.

Growth of Boron Carbide Crystals from a Copper Flux

2009 ◽  
Vol 1164 ◽  
Author(s):  
Yi Zhang ◽  
James Edgar ◽  
Jack Plummer ◽  
Clinton Whiteley ◽  
Hui Chen ◽  
...  
Keyword(s):  
Boron Carbide ◽  
Potassium Hydroxide ◽  
Crystal Size ◽  
Optical Microscope ◽  
Etch Pit Density ◽  
Bulk Crystals ◽  
Limited Growth ◽  
Etch Pits ◽  
X Ray ◽  
Etch Pit

AbstractBoron carbide crystals ranging in size from 50 microns to several millimeters have been grown from a copper-boron carbide flux at temperatures from 1500°C to 1750°C. The crystal size increased with growth temperature although copper evaporation limited growth at the higher temperatures. Synchrotron X-ray Laue patterns were indexed according to (001) orientation boron carbide structure, indicating the bulk crystals were single crystalline with {001} growth facets. Raman spectrum of boron carbide indicates an improved crystal quality compared to the source powder, but peaks of crystals grown from 11B -enriched source shifted to the lower energy by 1-4 cm−1 from literature values, possibly due to the boron isotope dependency. Five fold symmetry defects and twin planes were common as observed by optical microscope and scanning electron microscope. Raindrop shape etch pits were formed after defect selective etching in molten potassium hydroxide at 600°C for 6 minutes. Typically, the etch pit density was on the order of 106/cm2.

A study of etch pit density and x-ray rocking curves for GaAs substrate evaluation

1991 ◽  
Vol 20 (5) ◽  
pp. 345-352 ◽  
Author(s):  
J. M. Tartaglia ◽  
S. M. Crochiere ◽  
C. E. Kalnas ◽  
D. L. Farrington ◽  
J. A. Kronwasser ◽  
...  
Keyword(s):  
Gaas Substrate ◽  
Etch Pit Density ◽  
X Ray ◽  
Etch Pit

I-V, C-V, and Hall Effect Studies of Indium-Doped Lpe GaAs

1988 ◽  
Vol 144 ◽  
Author(s):  
J.F. Chen ◽  
K. Xie ◽  
C.R. Wie
Keyword(s):  
Carrier Concentration ◽  
Field Emission ◽  
Schottky Diodes ◽  
Thermionic Emission ◽  
Etch Pit Density ◽  
Trap State ◽  
Etch Pit ◽  
Forward Current ◽  
In Doping ◽  
Thermionic Field Emission

ABSTRACTWe have studied the effects of In doping on the electrical properties of a liquid phase epitaxially (LPE) grown GaAs. The I–V characteristics of Au-GaAs Schottky diodes show, for the layer with In concentration of 2.4 × 1019 cm−3, an ideality factor close to 1.04 over more than seven decades of current. For the same sample, the reverse I–V characteristics are close to an ideal Schottky diode and can be fitted by a theoretical curve, combining the thermionic field emission and thermionic emission. The electrical improvement is closely related to the low etch pit density and other structural improvements. This indicates that, as in the LEC growth, In has effects on the reduction of disloation density in the LPE grown GaAs epi-layer. For doping levels higher than 6×1019 cm−3, an excess forward current is produced at low voltages and low temperatures. A large leakage current is observed under the reverse bias. This property is attributed to a high field effect, with field emission via a trap state as the most likely cause. Hall measurements showed that the ratio of free-carrier concentration ND−NA to the total-carrier concentration ND+NA increased with increasing In concentration.

The Monolithic Double-Crystal Spectrometer: Theory and Design Principles

1997 ◽  
Vol 30 (1) ◽  
pp. 7-15 ◽  
Author(s):  
O. Gang ◽  
M. Deutsch
Keyword(s):  
Emission Spectra ◽  
Dynamical Theory ◽  
Perfect Crystal ◽  
Energy Scale ◽  
Crystal Spectrometer ◽  
Double Crystal ◽  
Transmitted Radiation ◽  
Scanning Angle ◽  
Spectroscopic Measurements ◽  
X Ray

The monolithic double-crystal spectrometer (MDCS) is a perfect-crystal device allowing X-ray spectroscopic measurements on an absolute energy scale with an accuracy of better than 1 in 106. This paper presents a detailed analysis of its properties using the dynamical theory of X-ray propagation in perfect crystals. The transmitted wavelength, the transmission window profile, the energy dispersion and the integrated intensity of the transmitted radiation and their dependence on the scanning angle of rotation are derived. The polarization mixing is shown to have a subtle yet important effect on the transmission of the MDCS. An example of a specific MDCS, designed for measuring the Cu Kβ emission spectra, is discussed in detail. The results of the study highlight the advantages and limitations of this device and yield tools for optimizing the MDCS for a wide class of X-ray spectroscopic measurements and for correcting the inevitable, although minimal, distortions introduced by the finite instrumental window of the device.

Rapid Structural Defect Mapping of Bulk II-VI Semiconductors Using White-Beam Synchrotron Topography and X-ray Rocking Curve Analysis

1992 ◽  
Vol 262 ◽  
Author(s):  
Don Di Marzio ◽  
Louis G. Casagrande ◽  
Myung B. Lee ◽  
Thomas Fanning ◽  
Michael Dudley
Keyword(s):  
Semiconductor Industry ◽  
Defect Analysis ◽  
Etch Pit Density ◽  
Ir Detector ◽  
Rocking Curve ◽  
X Ray ◽  
Etch Pit ◽  
White Beam ◽  
Device Structures ◽  
Nondestructive Characterization

ABSTRACTNondestructive characterization techniques for substrates, epilayers, and device structures are becoming increasingly important in the semiconductor industry. Synchrotron-based white-beam x-ray topography, x-ray rocking curve measurements, and etch pit density were used to map the defect structure in a variety of CdTe and CdZnTe single crystal substrates, which are important for IR detector applications involving HgCdTe. Defects such as low angle grain boundaries have been successfully correlated using topography, rocking curves, and etch pit density, and twins have been observed using topography and rocking curves. The effectiveness of white-beam synchrotron topography for rapid and nondestructive defect analysis and substrate screening is discussed.

Growth and Characterization of High Quality, Low Defect, Subgrain Free Cadmium Telluride by a Modified Horizontal Bridgman Technique

1986 ◽  
Vol 90 ◽  
Author(s):  
W. P. Allred ◽  
A. A. Khan ◽  
C. J. Johnson ◽  
N. C. Giles ◽  
J. F. Schetzina
Keyword(s):  
Large Area ◽  
Bridgman Technique ◽  
Ir Detector ◽  
Double Crystal ◽  
X Ray ◽  
Etch Pit ◽  
Donor And Acceptor ◽  
Vertical Bridgman ◽  
Detector Materials

ABSTRACTA low stress modified horizontal Bridgman technique has been developed and used to grow low defect, large area, subgrain free CdTe crystals for use as substrates in the epitaxial growth of HgCdTe and related IR detector materials. CdTe wafers cut from horizontal Bridgman grown boules exhibit, resistivities in the 107ohm-cm range. Etch pit counts are in the 104cm−2 range. Etch pit patterns as well as x-ray topographs indicate the absence of low-angle grain boundaries. Double crystal x-ray rocking curves are single peaked and very narrow with FWHM(333) as low as 9 arc-sec. Rocking curves of FWHM(333) = 9 to 15 arc-sec, measured at several different laboratories, have been obtained for CdTe wafers cut from several boules. This is in contrast to standard vertical Bridgman grown CdTe samples, which generally show broader x-ray rocking curves sometimes with multiple peaks as a result of subrgrain structure. Low temperature (1.6–4.5 K) photoluminescence (PL) measurements on these low defect samples reveal bright edge emission lines which are the main feature of the spectrum. Additional bound exciton lines and other sharp features associated with donor and acceptor impurities are also present. The very weak defect band luminescence (1.40–1.46 eV) provides additional evidence of sample quality.

Nano-probe x-ray analysis and high-resolution imaging on planar defects in high-pressure synthesized infinite-layer superconductor

1994 ◽  
Vol 52 ◽  
pp. 728-729
Author(s):  
Y. Y. Wang ◽  
H. Zhang ◽  
V. P. Dravid ◽  
H. Zhang ◽  
L. D. Marks ◽  
...  
Keyword(s):  
High Pressure ◽  
High Resolution ◽  
Atomic Structure ◽  
Emission Spectra ◽  
High Resolution Electron Microscopy ◽  
Planar Defects ◽  
X Ray ◽  
Infinite Layer ◽  
Resolution Electron ◽  
Resolution Imaging

Azuma et al. observed planar defects in a high pressure synthesized infinitelayer compound (i.e. ACuO2 (A=cation)), which exhibits superconductivity at ~110 K. It was proposed that the defects are cation deficient and that the superconductivity in this material is related to the planar defects. In this report, we present quantitative analysis of the planar defects utilizing nanometer probe xray microanalysis, high resolution electron microscopy, and image simulation to determine the chemical composition and atomic structure of the planar defects. We propose an atomic structure model for the planar defects.Infinite-layer samples with the nominal chemical formula, (Sr1-xCax)yCuO2 (x=0.3; y=0.9,1.0,1.1), were prepared using solid state synthesized low pressure forms of (Sr1-xCax)CuO2 with additions of CuO or (Sr1-xCax)2CuO3, followed by a high pressure treatment.Quantitative x-ray microanalysis, with a 1 nm probe, was performed using a cold field emission gun TEM (Hitachi HF-2000) equipped with an Oxford Pentafet thin-window x-ray detector. The probe was positioned on the planar defects, which has a 0.74 nm width, and x-ray emission spectra from the defects were compared with those obtained from vicinity regions.

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