Influence of indium doping on AlGaAs layers grown by molecular beam epitaxy

Abstract

Influence of indium doping on the qualities of AlGaAs layers grown by molecular beam epitaxy has been studied. It was found that a proper amount of In doping can increase the photoluminescence intensity drastically by a factor greater than 10 indicating an improvement in the optical quality of AlGaAs epilayers. The improvement in the material quality is attributed to a higher surface migration rate of In atoms than those of Ga and Al atoms leading to a reduction of group III vacancies. However, too great a concentration of In atoms leads to effects that may degrade the film quality.

Optical properties of AlAs/GaAs quantum wells with antimony as a surfactant by solid source molecular beam epitaxy

“…As an isoelectronic dopant, Sb reduces deep levels which improves crystalline quality of AlAs barrier layers. Because Al has a lower surface migration rate, vacancies are more easily formed in AlAs resulting in poorer material quality [15], and Al vacancies have been shown to be the source of deep traps in MBE-grown AlAs [18,19], Al vacancies are reduced by the Sb isoelectronic dopant [7]. Furthermore, reduction of nonradiative recombination centers in the presence of Sb flux may also be due to the passivation of electron traps such as Al-vacancies or Al-vacancy containing complexes by a small amount of incorporated antimony [5].…”

“…For samples B, C, and D, however, as the Sb concentration increases from 0.2% to 0.8%, the PL intensity drops and the linewidth widens, indicating that Sb is a surfactant as well as an alloy constituent. The deterioration of the PL performance results from the straininduced defects in the AlAs barriers with an increase of Sb [15]. In order to explain Sb as a surfactant on the improvement of surface roughness, we use the infinite square potential well model to describe the relation of the interface roughness and linewidth.…”