A theoretical study of variation of photoionization cross section of donor impurities in a GaAs quantum dot of cylindrical geometry with incident photon frequency, donor location along the dot axis and applied uniaxial stress

In this work, we have used a variational technique within the effective mass approximation to study the variation of the photoionization cross section of a donor impurity in a cylindrical GaAs quantum dot with incident photon frequencies and applied uniaxial stress. We have used the dipole approximation and assumed that the barrier potential is infinite. Our results show that the photoionization cross section begins at a finite value and increases with increasing frequency until it reaches a peak and then it decreases gradually, almost exponentially, until it reaches a finite value when it is almost insensitive to any further increase in frequency. Furthermore, for a particular quantum dot length, the photoionization cross section decreases with increasing applied uniaxial stress. We have also noted that the longer the quantum well dot the larger is the photoionization cross section