Energy levels in self-assembled InAs/GaAs quantum dots above the pressure-inducedΓ−Xcrossover

Low-temperature photoluminescence (PL) studies of InAs self-assembled quantum dots (SAQD’s) embedded in a GaAs matrix have been performed under hydrostatic pressure $P$ up to 70 kbar. A strong blueshift of the PL line from the SAQD’s with $P$ up to 53 kbar changes to a relatively small redshift at higher $P.\mathrm{}$ This is the fingerprint of a $\Gamma -X$ crossover. Above the crossover pressure, we find experimental evidence for type-II band alignment in the InAs SAQD/GaAs heterostructure system. This gives a reference point that allows us to determine independently the energies of the electron and hole levels in the QD.