Silicon-Germanium Alloys for Infrared Detectors.
Interim rept. 15 Aug 77-15 Aug 78,
HUGHES RESEARCH LABS MALIBU CALIF
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Silicon-germanium alloys in the range of 10 at . germanium have been prepared and investigated. The object of the program is to prepare intrinsic Si-Ge with high enough absorption at 1.06 micrometers to be suitable for detectors at that wavelength and to investigate whether the changes in energy levels and optical properties of doped Si-Ge offer advantages for monolithic focal plane array applications over the corresponding doped silicon. The first years work concentrated mostly on growing intrinsic material. After some attempts to prepare crystals by growing a succession of seeds of increasing Ge content, we found that alloys with greater than 10 Ge could be grown by the Czochralski technique directly from 0.5 or even 0 Ge seeds if a suitable growth rate was chosen. The necessary slow growth rate to achieve single crystals necessitated long exposures of the melt to contamination from the crucible, but the use of high-purity synthetic quartz crucibles reduced the uptake of electrically active impurties. Measurements on alloys that were not intentionally doped yielded values for the shift in the energy level of boron from the case of a pure silicon host that were in agreement with the literature.
- Infrared Detection and Detectors
- Solid State Physics