Localized vibrational modes of light impurities in gallium phosphide. (Absorption spectra)

Abstract

Vibrational absorption due to boron, carbon, nitrogen, silicon, aluminium and arsenic has been observed in gallium phosphide crystals. It is concluded that ¹¹B and ¹⁰B give gap modes with a separation of about 1.5 cm^-1. Previously reported absorption bands at 849 and 882 cm^-1 have only been detected in electron irradiated zinc doped crystals, and it would appear that they cannot be due to local+gap combinations. It has been confirmed that a line at 496 cm^-1 is due to ¹⁴N, and it has been shown unambiguously that another line at 465 cm^-1 is due to silicon as a result of observed isotopic splittings. Mass spectrographic and electrical measurements made on some of the samples examined has allowed estimates to be made of the apparent charges associated with the various impurities.