Elucidation of x-ray diffraction data on the nature of the ordering of GaInP2 and how the ordering relates to changes in the optical properties

The relationship between anomalous changes in the band gap and ordering of the group III sublattice of GaInP2 is discussed. X-ray diffraction data are reported for the first time which show significant long-range order of the CuPt type, i.e., alternating {111} Ga and In planes, in agreement with published electron diffraction data. However, the x-ray and electron diffraction data differ as to which of the four possible orientations are observed and as to the directions of the streaks. No correlation was observed between the long-range order parameter and the band-gap anomalies.