BAND-GAP REDUCTION AND VALENCE-BAND SPLITTING OF ORDERED GAINP2

Low-temperature photoluminescence excitation spectra are used to determine the order-dependent parameters: valence-band splitting and band-gap reduction in spontaneously ordered GaInP2. Effects due to composition fluctuations between different samples and the associated strain, as well as the excitonic binding energies, have been properly taken into account to yield accurate band-gap reduction and valence-band splitting values. The results from recently published ab initio band structure calculations are used to extrapolate the band-gap reduction from the strongest experimentally realized degree of ordering to perfect ordering. We find a total band-gap reduction of 471+/-12 meV, which is very close to recent theoretical predictions. (C) 1995 American Institute of Physics.