We describe studies of luminescence and lateral transport properties of excited carriers in GaAs- A1GaAs multiple quantum well (MQW) structures by cathodoluminescence measurements in a scanning electron microscope. We examine the effect of in-plane, etch-defined feature size on MQW luminescence efficiency and variability, and determine the diffusion length and its temperature dependence from ˜ 8K to 250K. Our measurements also provide information about nonradiative surface recombination velocity at the side walls of etch-defined MQW structures.

Raman spectroscopy is used to characterize silicon implanted with arsenic and then annealed. The implant dose ranged from 2 × 1012 to 2 × 1013/cm2. The as-implanted samples show a decreased Raman intensity of the 520 cm−1 optical mode, and increased Raman intensity between 400 and 500 cm−1 with respect to an unimplanted silicon wafer. The higher arsenic doses show an increase in the second-order transverse acoustic-mode (TA) intensity around 300 cm−1 relative to the secondorder transverse optical-mode (TO) intensity near 970 cm−1. Annealing restores the 2TA/2TO relative intensities and sharpens the weak peaks between 600 and 900 cm−1. The Raman spectrum is altered by the lowest dose implant and the annealing steps do not lead to a complete recovery of the pre-implant Raman spectrum. This permits the monitoring of lowdose ion-implant damage recovery with Raman spectroscopy.

We describe the characteristics and performance of a combined desk-side high resolution X-ray diffractometer and room temperature photoluminescence spectrometer designed for rapid mapping of compound semiconductors in a production line context. The combined data for AIGaAs on GaAs suggest that recent measurements of the lattice constant and the Poisson ratio of AlAs may be more reliable than earlier published values. We illustrate the instrument performance in showing that for lattice matched ternary GaInP on GaAs systems, the X-ray rocking curve maps are much more sensitive to composition variation than the photoluminescence spectra.

Crystals of silicon carbide, and other polytypic materials often have micropipes associated with screw dislocations of large Burgers vectors running along their axial dimensions. These defects are considered the most deleterious to the performance of SiC semiconductor devices.

Optical micrographs of micropipes in silicon carbide crystals are ordinarily faint. To obtain micrographs showing higher contrast and detail, laser scanning confocal microscopy (LSCM) and simple fluorescence microscopy were used on 6H-SiC single crystals after infiltrating them with a low-viscosity epoxy containing a fluorescent dye. “Staining” the micropipes rendered them much more visible both in fluorescence and conventional optical microscopies. Details of their structures and shapes were revealed, and their dimensions were measured accurately, using LSCM and other, less sophisticated, fluorescence microscopies. Other voids present, such as microcracks, were also visualized. Observations by this optical technique were related to information obtained by synchrotron white beam x-ray topography.

The influence of the material composition on the optical properties of the quaternary compound semiconductor system ZnGe(AsxP1-x)2 was studied for the first time. The crystals have been synthesized by direct solidification from a stoichiometric melt. X-ray diffraction measurements revealed a chalcopyrite type lattice for the quaternary compound. Closer examination by energy dispersive X-ray microprobe analysis yielded the exact element concentrations for the As and P components. Then electrolyte electroreflectance (EER) spectroscopy was used to determine the energies of the fundamental optical transitions as a function of the composition x. The analysis shows an approximately linear increase of the direct band gap with decreasing As content.

Furthermore, the influence of the composition on the splitting and ordering of the three highest valence bands was investigated by polarization dependent EER measurements. The spectra for two samples with x = 0.42 and 0.77 allowed the determination of the spin orbit parameter Aso and the crystal field parameter Δ;cf by using the quasicubic model. The values were found close to calculated ones, obtained by the same model under the assumption of a precise linear dependence of the band gap on the composition x.

This paper reports etching results supporting the identification of the SG1 center as a germanium dangling bond defect at the interface between an oxide and crystalline SiGe. The presence of this defect is significant because, like an analogous center in Si-based systems, it may alter the operation of any microelectronic or micro-optical device which incorporates an interface between SiGe and an overlying oxide. The samples examined are oxygen implanted SiGe layers in which the SG 1 center is believed to occur at the interface between oxide precipitates and SiGe. Because of the center's apparent relation to the oxide precipitates distributed through layers of the sample, a depth profile assists in confirming the interfacial nature of the defect. We obtain a depth profile by comparing electron paramagnetic resonance (EPR) spectra of samples etched to decreasing thickness. EPR spectra indicate that the SG1 center decreases with depth in a manner that when correlated to a cross sectional transmission electron micrograph confirms the association with Si0 2 and supports its location at the SiGe/SiO2 precipitate interface.