ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The presence of oxygen in silicon-germanium can have a significant effect on the sintering, microstructural, and transport properties of these alloys. A neutron activation study was performed to follow the total oxygen content during the preparation of mechanically alloyed n-type Si-20 at. % Ge alloys using either fine powders, polycrystalline Czochralski chunk, or single-crystal float zoned starting materials. The alloys were prepared with a nominal composition of Si0.747Ge0.187(GaP)0.016P0.034. The total oxygen concentration was measured in the starting materials, after 6 h of mechanical alloying in a helium environment, after hot pressing, and after a 3 h, 1100 °C heat treatment in fused silica ampoules. Alloys that contained oxygen levels in excess of 2.0 at. % exhibited low carrier mobility and low thermal conductivity, whereas those that contained less than 0.6 at. % oxygen possessed high mobility and thermal conductivity. The microstructure, as observed by optical metallography and scanning electron microscopy, was found to differ greatly with oxygen content as the low oxygen alloys showed relatively large, well-defined grains and the high oxygen alloys showed evidence of poor sintering and limited grain growth.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.351702
