STATE MIXING IN INAS/GAAS QUANTUM DOTS AT THE PRESSURE-INDUCED GAMMA-X CROSSING

We have measured low-temperature (T=10 K) photoluminescence spectra of InAs quantum dots embedded in a GaAs crystalline matrix under hydrostatic pressures up to 7 GPa. Below 4.2 GPa the spectra are dominated by the emission related to the -like electron heavy-hole exciton in the InAs dots. Above 4.2 GPa the spectra show two luminescence bands that shift to lower energies with increasing pressure. These bands are attributed to the type-I transition between Xxy and heavy-hole states in the dots and the type-II transition from X states in GaAs to InAs heavy-hole states, respectively. In the -X crossover regime we find evidence for a pronounced anticrossing behavior due to mixing between InAs -like and GaAs X-like states. The corresponding interaction potential is estimated to be 9 meV, which is an order of magnitude larger compared to mixing interactions reported for semiconductor superlattices. © 1994 The American Physical Society.