LOW-TEMPERATURE LUMINESCENT PROPERTIES OF DEGENERATE P-TYPE GAAS GROWN BY LOW-PRESSURE METALORGANIC CHEMICAL-VAPOR-DEPOSITION

Low-temperature (20 K) luminescent properties of heavily carbon- and z inc-doped GaAs grown by low-pressure metalorganic chemical vapor depos ition were investigated. The luminescence linewidth became broader at low temperatures when p > 4 X 10(19) cm-3 due to the appearance of a s houlder peak. The main peak shifted to low energy when the dopant conc entration was increased; however, the shoulder peak was at around 1.48 5 eV and was nearly independent of the dopant concentration. The peak of the band-to-acceptor transition occurred at low temperature and dom inated the emission spectra of degenerate GaAs. The peak energy of Zn- doped samples was lower than that of C-doped samples because of the ex istence of defects. The excitation power intensity was varied to inves tigate the behavior of the shoulder peak for both types of dopants. Th e shoulder peak was a part of the main peak because of the recombinati on between the conduction band and the bottom of the impurity band.