MAGNETOLUMINESCENCE STUDY ON THE EFFECTIVE-MASS ANISOTROPY OF CUPTB-ORDERED GAINP2 ALLOYS

Photoluminescence measurements in a magnetic held between 0 and 13.6 T were carried out on CuPtB-ordered GaInP at liquid-helium temperature. Four samples of different degrees of ordering (eta, varying from 0 to 0.54) were studied. Experimental results show that the ordering not o nly induces a band-gap reduction and valence-band splitting, it also c auses changes in effective masses and an effective mass anisotropy. By measuring and analyzing the magnetoluminescence with the magnetic hel d aligned along both ordering (the [(1) over bar 11]) and growth (the [001]) directions, we demonstrate that, for the band-edge excitonic st ate, the reduced mass in the plane perpendicular to the ordering direc tion is smaller than that in the ordering direction and also smaller t han that of a disordered ahoy. The exciton binding energy is found nea rly independent of the degree of ordering, in agreement with theoretic al predictions. (C) 1997 American Institute of Physics.