HYDROSTATIC-PRESSURE DEPENDENCE OF BAND OFFSETS IN GAAS/ALXGA1-XAS HETEROSTRUCTURES

We have determined the pressure dependences of the band offsets in the GaAs/AlxGa1-xAs heterojunctions by measuring the pressure dependences of the harmonic-oscillator-like electron-energy-level spacings HBARomega(e) of two AlxGa1-xAs parabolic quantum wells at hydrostatic pressures up to approximately 26 kbar at 2 K using photoluminescence-excitation spectroscopy. We found that the conduction-band offset for x almost-equal-to 0.3 increases with pressure at a rate of 0.73+/-0.25 meV/kbar. Using this result and the finding that the pressure coefficient of the direct-band-gap energy of AlxGa1-xAs is independent of x for x = 0-0.4, we found that the fractional conduction- (valence-) band offset Q(c) (Q(v)) of GaAs/AlxGa1-xAs increases (decreases) with pressure at a rate of 0.0020+/-0.0007 kbar-1. From this result, we conclude that the previous determinations of the band-offset values of GaAs/AlxGa1-xAs by high-pressure measurements overestimated (underestimated) the fractional conduction- (valence-) band offset by 0.06+/-0.02, and the corrected Q(c) value at atmospheric pressure should be 0.63+/-0.04.