Experimental Study of Optical Transitions in Be-Doped GaAs/AlAs Multiple Quantum Wells

Abstract

We present a photoluminescence study of optical transitions in Be acceptor-doped GaAs/AlAs multiple quantum wells at room and liquid nitrogen temperatures. We investigate excitonic spectra and reveal acceptor--impurity induced effects in multiple quantum wells having different width.

Behaviour of optical transitions in GaAs/AlAs with highly Be δ-doped MQWs

“…However, for highly doped samples the e-Be_B and excitonic PL bands were approximated with a Gaussian lineshape, and band-to-band transitions were calculated adapting the FDS formalism with a Gaussian lineshape convolution. This approximation is consistent with the PL spectra if some fraction of the excitons are bound to acceptor impurities at low temperatures [14]. The calcu- lated spectra at liquid nitrogen and room temperatures are shown in Fig.…”

“…It is important to notice that in the PL spec-tra the transitions associated with Be acceptors have not been observed, too. The radiative recombination of free electrons with acceptors (e-Be) is characteristic of Be doped MQWs [14]. The absence of this line could be due to the weak doping of the reference sample.…”

“…1 by the label e-Be_B. In weakly doped MQWs the influence of impurity recombination in the PL spectra at room temperature is negligible [14]. Because the binding energy of acceptors is high enough, not all acceptors are ionized at room temperature.…”

Excitonic and impurity-related optical transitions in Beδ-dopedGaAs∕AlAsmultiple quantum wells: Fractional-dimensional space approach

“…86͒ and GaAs/ AlAs MQWs. 87 The LO-phonon interaction causes a redshift of the threshold energy, 88 whose value is a few meV, and there was an observed discrepancy between the threshold energy and acceptor binding energy in our experiments. This is the reason why, in order to overcome this effect, the true freeelectron-acceptor transition energy should be interpreted close to the maximum of the PL spectra.…”