Photoluminescence of Be implanted Si-doped GaAs

Degenerately doped n-type GaAs produces band-to-band luminescence with the peak energy dependent on the carrier concentration. In this study the photoluminescence of Si-doped GaAs is examined after implantation with high energy Be ions and annealing. The band-to-band peak energy in the unimplanted (reference) material is shown to be smaller than reported values in Te-doped GaAs of the same carrier concentration. This is attributed to compensation in the Si doped material as a result of its amphoteric nature. For the implanted samples, no luminescence was recorded for the unannealed samples or those annealed at 400 degrees C and 500 degrees C. Comparing the relative peak intensities from material annealed at 600 degrees C for 15 min and 30 min indicates an increase in the number of As vacancies with anneal time. For samples annealed at 700 degrees C and 800 degrees C, the dominant luminescence is associated with Ga-As antisite defects. It is suggested that formation of these defects occurs predominantly only at these higher temperatures. Crystal recovery as measured by the luminescence intensity increased with both anneal temperature and time. For the implanted sample annealed at 800 degrees C for 15 min, the dominant peak height was 25% of that from the reference sample.