No abstract

The electroluminescent properties of GaAs1−xPx light-emitting diodes with and without nitrogen doping have been studied at temperatures from 77 to 300 °K. The radiative transitions in the indirect band-gap region have been identified by a comparison of the emission spectra with those obtained in GaP. At 77 °K nitrogen-free GaAsP recombination consists of three peaks, shallow donor-acceptor pair transitions, free-exciton transitions (which are not observed in pure GaP), and LA phonon-assisted free-exciton transitions. As the temperature is increased, the free excitons and/or free electron-hole transitions become dominant. The indirect energy band gap has been found to exhibit appreciable curvature. The alloy composition at which the direct-indirect energy band-gap transition occurs has been found to be xc=0.46 at 77 °K and 0.49 at 300 °K. In nitrogen-doped GaAsP the 77 °K emission is dominated by transitions associated with nitrogen. For alloy compositions near GaP (x ≥ 0.9) a series of distinct peaks are observed, corresponding to the sharp-line nitrogen spectrum commonly observed in GaP. For x<0.80 the distinct peaks converge into a single broad band. Optical-absorption measurements indicate that both the depth and width of the nitrogen absorption band increase with increasing As concentration. The electroluminescent recombination for x < 0.80 has been found to occur primarily in a NN pair band, the high-energy onset of the EL band corresponding roughly to the center of the absorption band.

No abstract

High oxygen wafers from 100 mm diam Si crystals grown by the Czochralski process, but subjected to three different thermal histories in an experimental puller, were examined by Wright etching, transmission electron microscopy, and Fourier transform infrared spectroscopy after wafer heat-treatments at 775 ~ 1050 ~ 775 ~ + 1050 ~ and 1320 ~ + 775 ~ + 1050~ Only wafers near the seed end of each ingot were used, thus minimizing differences in parameters other than thermal history. The observations show that defect morphology and O precipitate number density (not total O precipitation) after the one-and two-step heat-treatments depend on thermal history in the puller. In particular, 775~ heated wafers which spent less than an hour in the puller below 1000~ show number densities down by more than a factor of 100 from those which spent longer. On the other hand, the observations indicate that effects of puller thermal history are erased with a short 1320~ anneal, or typical VLSI multistep pretreatments which enhance bulk oxygen precipitation. In addition, the results suggest two possible complications for simple models of oxygen precipitation. These are that 500~ annealing can be much more effective than 775~ annealing for nucleating oxygen precipitates, contrary to model predictions, and that critical sizes for precipitate dissolution at 1050~ can be much larger than predicted by classical calculations.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.255.6.125 Downloaded on 2015-06-05 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.255.6.125 Downloaded on 2015-06-05 to IP

No abstract

No abstract

No abstract

An investigation is reported into the origins of the oxygen evolutions observed in gas fusion analysis of oxygen in silicon. Oxygen evolution arising from surface contamination, surface oxide, and bulk oxygen have been identified. By maintaining the samples slightly below the melting temperature for 60s prior to melting, it was found that surface contaminants and oxide could be largely driven off and thereby separated from the bulk oxygen signal. However, a small component of surface oxide was found to carry over into the melting stage. Some instrumental causes for this carry over have been ruled out leaving as a possible explanation a highly stable oxygen containing surface phase.