VALENCE-BAND OFFSETS IN STRAINED GAAS1-XPX/GAAS HETEROJUNCTIONS

Valence band offsets at [100]-oriented heterojunctions between tensile-strained GaAs1-xPx and unstrained GaAs are studied experimentally and theoretically. Light-hole (LH) and heavy-hole (HH) offsets are first extracted from the well-width dependence of valence subband splittings observed in luminescence spectra of tensile-strained GaAs1-xPx/GaAs quantum wells of various compositions (x = 0.06, 0.09, and 0.19). This data is then combined with results from two other laboratories, yielding a set of 30 independent experimental offset values for junctions with compositions throughout the range 0.06 less than or equal to x less than or equal to 0.32. The data are found to be highly consistent, with linear fits Delta E(LH) = -140x (meV) and Delta E(HH) = -401x (meV) describing the measured offsets to within less than 5 meV on average. Experimental results are then compared with theoretical predictions for the GaAs1-xPx/GaAs system obtained from a tight-binding model for strained heterojunctions. Predictions from the tight-binding calculations are found to lie within experimental scatter for the LH offsets, which define the valence band edge in these heterostructures, while magnitudes of the tight-binding HH offsets exceed measured values by similar to 20% on average.