Abstract
The fluorescence of n‐ and p‐type GaAs0.7P0.3 under conditions of optical excitation is described. Measurements were made at 300 and 77 °K. In the as‐grown state the crystals were n‐type. They were made p‐type by diffusing in zinc and comparison was made between the fluorescence of the n‐ and p‐type specimens. At 77 °K, low‐energy spectral lines were found in the p‐type specimens in addition to that due to recombination via the zinc centre. One of these has an intensity which depends on the position of the Fermi level. Another of them appears to be associated with the presence of arsenic vacancies.