HIGH-PRESSURE STUDY OF GAMMA-X MIXING IN INAS GAAS QUANTUM DOTS/

We have measured low-temperature photoluminescence spectra of InAs qua ntum dots embedded in a GaAs crystalline matrix under hydrostatic pres sures up to 7 GPa. Below 4.2 GPa the spectra are dominated by the Gamm a-like electron-heavy hole (HH) exciton transition in the InAs dots. A bove 4.2 GPa the spectra show two X-related luminescence bands which a re attributed to the indirect type-I transition between X(Xy) and HH s tates of the dots and the type-II transition from X states in GaAs to InAs HH states, respectively. In the Gamma-X crossover regime we find evidence for a pronounced mixing interaction between InAs Gamma-like a nd GaAs X-like states. The corresponding interaction potential is esti mated to be 9 meV.