Photoluminescence of Gallium Phosphide.

The photoluminescence emission spectra from four GaP crystals were studied in order to characterize their impurity content. The temperature dependent behavior of the emission spectra was studied in the temperature range of 4.2 degrees Kelvin to 100 degrees Kelvin using liquid helium and the cold gas from evaporating liquid helium as the coolant. An argon-ion laser operating at 4579A and 150mw power output was used to excite the crystals, and the spectra were detected photoelectrically. The inadvertent impurities present in the crystals are nitrogen, sulfur, carbon, and silicon, with nitrogen related spectra seen in only one sample. Copper doping in one sample seemed to eliminate any evidence of silicon contamination, but switching from quartz to graphite growth crucibles did not. Two distinct spectral features were seen that were not readily identifiable from the literature, and these were attributed to the presence of silicon. Author