Band-Gap Energy Anomaly and Sublattice Ordering in GaInP and AlGaInP Grown by Metalorganic Vapor Phase Epitaxy

The previously reported photoluminescence(PL)-peak-energy anomaly problem for Ga 0.5 In 0.5 P grown on GaAs by metalorganic vapor phase epitaxy (MOVPE) was studied in detail. X-ray microprobe analysis, and optical transmission spectra measurements were carried out to examine alloy compositions and band-gap energies ( E g s), respectively. The MOVPE growth condition dependence of {1/2, 1/2, 1/2} superlattices (SLs) on the cation sublattice in Ga 0.5 In 0.5 P was studied in detail, using transmission electron microscopy. The correlation between the E g anomaly and the SLs was examined in detail and established. Raman spectra seemed to show zone-folding effects due to the monolayer SL. A similar E g anomaly was reported for AlGaInP. AlGaInP and AlInP were also found to show the same SLs.