BAND-OFFSET DETERMINATION FOR GAINP-ALGAINP STRUCTURES WITH COMPRESSIVELY STRAINED-QUANTUM-WELL ACTIVE LAYERS

(AlGaIn)P-on-GaAs structures incorporating compressively strained Ga1-xInxP (x>0.48) quantum well active layers have been studied by low-temperature photoluminescence excitation spectroscopy. The splitting between the lowest energy heavy- and light-hole excitonic transitions is observed to be only weakly dependent on well width over the range 25-300 Angstrom, for sample sets with x=0.56 and x=0.59. Envelope function approximation fitting, based on bulk valence band dispersion calculations which include the strain-induced interaction with the spin split-off band, shows this splitting behavior to be a sensitive function of the heterojunction band offset. Conduction band discontinuities, Delta E(c), of 0.67 Delta E(g) (x=0.56) and 0.85 Delta E(g) (x=0.59) provide the best fit to these and all higher lying transitions for the full range of structures examined, indicating that poor hole confinement is a limiting factor in practical compressive strain (AlGaIn)P laser device performance.