ORDERING ALONG [111] AND [100] DIRECTIONS IN GAINP DEMONSTRATED BY PHOTOLUMINESCENCE UNDER HYDROSTATIC-PRESSURE

Photoluminescence of GaInP epilayers under hydrostatic pressure is inv estigated. The Gamma valley of disordered GaInP shifts sublinearly upw ards with respect to the top of the valence band with increasing press ure and this sublinearity is caused by the nonlinear dependence of lat tice constant on the hydrostatic pressure. The Gamma valleys of ordere d GaInP epilayers rise slower than that of the disordered one. Conside ring the interactions between the Gamma valley and folded L and X vall eys, the pressure dependence of the band gap of ordered GaInP is calcu lated and fitted. The results demonstrate that not only ordering along [111] directions but also sometimes simultaneous ordering along [111] and [100] directions can occur in ordered GaInP. (C) 1996 American In stitute of Physics.