Radiative recombination in cylindrical GaAs-(Ga,Al)As quantum-well wires under quasistationary excitation conditions

Abstract

A quantum-mechanical calculation of radiative recombinations in cylindrical GaAs-͑Ga,Al͒As quantum-well wires excited by a cw laser in a photoluminescence experiment under quasistationary excitation conditions is performed. We work within the effective-mass approximation and the parabolic-band model for describing both electrons and holes, and consider, in the steady state, the interband absorption, and some radiative recombination mechanisms, such as recombination of electrons with free holes and with holes bound at acceptors. Carrier densities and electron-hole recombination decay times are calculated at room temperature and as functions of the laser intensity. For doped quantum-well wires, it is shown that the presence of acceptors substantially modifies the dependence on the laser intensity of the above quantities.

Photoluminescence in Cylindrical Quantum Well Wires in the Presence of Shallow Impurities and Magnetic Field

“…is the equilibrium density of electrons at temperature T. Also, Qn e Y n h is the rate of free electrons and holes at temperature T, and has the form [13] Qn e Y n h where m e (m h ) is the quasi-Fermi level of electrons (holes) measured from the first Landau level in the conduction (valence) band and b 1ak B T .…”

“…Similarly, the rate radiative recombination of electrons in the first Landau level with free holes in the valence band can be written [13] as…”

“…We will assume that the impurity acceptor concentration is small, that is a number in the range, N A % 10 14 to 10 17 cm À3 . The rate equation that describes the change in the density of electrons in the conduction band is given by [13] dn e dt…”

“…In addition, theoretical studies on the optical properties and on the electronic structure and recombination processes in QWW have been published, [11,12,13]. Experimental investigations have shown that recombination processes at low temperatures are dominated by excitons [9,10], since the confinement of electrons and holes inside the QWW not only produces a strong enhancement in the optical spectra but also gives rise to high optical nonlinearities which are of crucial importance for device application purposes.…”

“…We will follow the same theoretical lines as used in [13] and show the calculated carrier densities, quasi-Fermi level of electrons and holes and the lifetimes or recombination times associated with a few room temperature radiative recombination processes as a function of the intensity of the continuous-wave laser excitation.…”