THE EFFECTS OF BERYLLIUM DOPING IN INGAALAS LAYERS GROWN BY MOLECULAR-BEAM EPITAXY

This paper reports the effects of beryllium (Be) doping in In1-x-yGaxA lyAs layers grown lattice-matched to InP(1 0 0) substrates by molecula r beam epitaxy. Hall effect measurements showed that hole concentratio ns as high as 2.94 x 10(19) cm(-3) were achieved, and the concentratio n decreased with further increase in the Be cell temperature. Dependin g on the hole concentration, good optical quality was achieved as veri fied by photoluminescence (PL)measurements. X-ray diffraction measurem ents showed lattice mismatch values of lower than 8.6 x 10(-4) in most samples. An intense PL peak (5 K) at 1.089 eV which is attributed to band-acceptor ri combination was observed from the sample with the low est hole concentration of 2.28 x 10(16) cm(-3). This sample showed the lowest PL full-width at half-maximum of 8 meV (at 5 K) for the free e xciton recombination. To the best of our knowledge, this is the lowest value reported to date. An increase in the hole concentration caused a merging of the band-acceptor and free exciton recombination lines to form a broad PL spectrum. A shift in the free exciton peak position i n the PL spectrum was observed following an increase in the hole conce ntration, an effect which was probably due to degeneracy. (C) 1998 Els evier Science B.V. All rights reserved.