Photoionization cross-section of donor impurities in spherical GaAs quantum dots: hydrostatic pressure effects

Full text: Using a variational procedure for a hydrogenic donor-impurity we have calculated the photoionization cross-section in spherical GaAs quantum dots. We discuss the dependence on the photoionization cross-section for hydrogenic donor impurity in in nite and nite barrier quantum dots as a function of the size of the dot, impurity position, polarization of the photon, applied hydrostatic pressure, and normalized photon energy. For the nite case, calculations for the pressure effects are both in direct and indirect GaAsAl gap regime. We have considered the different transition rules that depend of the impurity position and photon polarization. Calculations are presented for impurity on-center, and o -center in the spherical quantum dots. We found that the photoionization cross-section increases with the applied hydrostatic pressure both for on-center and o - center impurities. The photoionization cross-section increases or decreases depending of the impurity position, photon polarization, and radius of dots. Also we have showed that the photoionization cross-section decreases as the normalized photon energy increases. The results we have obtained show that the photoionization cross- section is strongly a effected by the quantum dot size, and the position of the impurity. The measurement of photoionization in such systems would be of great interest in understanding the optical properties of carriers in quantum dots. (author)