CONDUCTION-BAND AND VALENCE-BAND EFFECTIVE MASSES IN SPONTANEOUSLY ORDERED GAINP2

An eight-band kp model is developed for zinc-blende semiconductor alloys that exhibit spontaneous CuPt ordering. Energy dispersions and effective masses are calculated analytically for the conduction band and valence band as a function of the degree of ordering. All the effective-mass tensors are found to be diagonal and the energy dispersions are ellipsoidal to terms quadratic in the wave vector when the axis of quantization (the z direction) is chosen along the ordering direction. The change of effective masses is found to satisfy a sum rule when ordering is weak. Numerical results are given for the ordered GaInP2 alloy. We find that, as the order parameter increases, along the ordering direction, m is unchanged for the heavy-hole band, increases for the light-hole band, and decreases for the spin-orbit split-off band. In the plane perpendicular to the ordering direction, m for the heavy- and light-hole bands decreases, whereas it increases for the split-off band. For the conduction band, both m and m decrease. © 1995 The American Physical Society.