Photoionization of impurities in infinite-barrier quantum wells

The Photoionization Cross-Section of Impurities in Quantum Dots

“…Photoionization cross-section as a function of the normalized photon energy hw=E s of a hydrogenic donor impurity placed at the center of a cubic GaAs quantum dot for several values of the quantum dot sizes. Curves (a), (b), and (c) correspond to the case of L x ¼ L y ¼ L z ¼ 3a * , 2a * , and 1a * , respectively wire, and it is thoroughly different when it is perpendicular, in which case the cross-section rises from zero absorption, reaches a maximum value, and then falls off with increasing photon energy [54,57,61].…”

“…The photon energy dependence of the photoionization cross-section in low-dimensional electronic systems is generally determined by the impurity ground state wavefunction, the potential which links the electron to the donor impurity and the conduction subband of the host crystal and by the wavefunction of the conduction subbands into which the charge carrier is excited. Recently, much attention has been devoted to the study of the hydrogenic impurity photoionization cross-section in systems with reduced dimensionality such as quantum wells [53][54][55][56][57][58] and quantum-well wires [59][60][61]. Most of these works can be summarized as follows: Takikawa et al [53] have experimentally and theoretically examined the photoionization of the deep traps in AlGaAs/GaAs multiple quantum well layers grown by metalorganic chemical vapour deposition.…”

“…They have determined the photoionization threshold energy, the amplitude, and the excitation energy dependence of the photoionization cross-section associated with a transition from a deep trap to subbands, assuming a delta function as a core potential for the deep level. El-Said and Tomak [54] have investigated the dependence of the photoionization crosssection on photon energy for shallow donors in infinite-barrier GaAs/Ga 1Àx Al x As quantum wells for incident light polarization assumed in the x-direction. The same work as before has been done for light polarized in the z-direction by considering optical transitions that take place from the impurity ground state as the initial state to the second subband as the final continuum state [55].…”

The polarizability and the photoionization cross‐section under the external fields for donor impurities in quantum well‐wire

“…The photoionization cross-section of hydrogenic impurities in bulk semiconductors is firstly investigated by Lax [1]. In recent years work has been done on the photoionization cross-section of hydrogenic impurities in structures of reduced dimensionally such as quantum wells (QWs), wires (QWWs) and quantum dots (QDs) [2][3][4][5][6][7][8][9][10][11][12][13].…”

Photoionization cross section and refractive-index change of hydrogenic impurities in a CdS-SiO2 spherical quantum dot

“…The dependence of the photoionization cross section on the photon energy in semiconductors for different impurity potentials has been investigated by Ilaiwi and Tomak [27]. Also, the effect of the well width [28] and the polarization direction of light [29] on the photoionization of impurities in both finite-and infinite-barrier quantum wells have been studied. In quantum-well wire structures, photoionization of impurities has been studied by Sali et al [30].…”