Band offsets of ${\mathrm{Ga}}_{0.5}$${\mathrm{In}}_{0.5}$P/GaAs single quantum wells from pressure-induced type-II transitions

We report on high-pressure, low-temperature photoluminescence of ${\mathrm{Ga}}_{0.5}$${\mathrm{In}}_{0.5}$P/GaAs single quantum wells grown by metalorganic-molecular-beam epitaxy. A type-I–type-II (and Γ-X) transition occurs at P=3.25±0.1 GPa for all well widths (from 10 to 70 Å), in contrast to what is observed in (Al,Ga)As/GaAs quantum wells. Using envelope-function calculations for the type-II transitions, a valence-band offset of 330±20 meV is deduced independent of pressure, within experimental precision. This is in good agreement with a previous photoreflectance study and with recent theoretical predictions on such heterostructures.