Molecular beam epitaxy and properties of GaAsBi/GaAs quantum wells grown by molecular beam epitaxy: effect of thermal annealing

Abstract

We have grown GaAsBi quantum wells by molecular beam epitaxy. We have studied the properties of a 7% Bi GaAsBi quantum well and their variation with thermal annealing. High-resolution X-ray diffraction, secondary ion mass spectrometry, and transmission electron microscopy have been employed to get some insight into its structural properties. Stationary and time-resolved photoluminescence shows that the quantum well emission, peaking at 1.23 μm at room temperature, can be improved by a rapid annealing at 650°C, while the use of a higher annealing temperature leads to emission degradation and blue-shifting due to the activation of non-radiative centers and bismuth diffusion from the quantum well.

Links between bismuth incorporation and surface reconstruction during GaAsBi growth probed by in situ measurements

“…The GaAsBi layers under study were grown with As 4 ; Ga and Bi shutters were simultaneously opened at the start of their growth. 18 For all the samples, a 300nm-thick GaAs buffer layer was grown at 580°C before ramping down the wafer temperature to perform GaAsBi growth. At each change of growth temperature care was taken to stabilize its value.…”

Influence of laser irradiation on optical properties of GaAsBi/GaAs quantum wells

“…Temperatures of 600-700°C used in rapid thermal annealing were shown to be sufficient for the restructuration of GaAsBi structures [9,12]. Since the photon energy of He-Cd laser radiation Fig.…”

“…It was demonstrated that RTA also caused a blue shift of the PL band. Although, it is still not clear if the emission shift is related to the Bi out-diffusion or to the microscale changes in the GaAsBi structure [12]. For thin GaAsBi structures, a decrease of defect density has been claimed to occur during annealing [9,10].…”

“…For thin GaAsBi structures, a decrease of defect density has been claimed to occur during annealing [9,10]. The PL intensity improvement might be associated with the reduction of bismuth clusters, as well as with the removal of defects related to arsenic and gallium [12][13][14]. The overall improvement in crystal quality during RTA might also be involved [7].…”

Theoretical calculations of absorption spectra of GaNAsBi-based MQWs operating at 1.55 μm

“…Indeed, Batool et al have grown a 7% Bi GaAsBi/GaAs QWs emitting at 1.23 mm by MBE with 7 nm QWs thickness [48]. It has been also demonstrated that annealing this QW at temperature higher than 650 C leads to bismuth out-diffusion and an amelioration of the photoluminescence emission [49]. Moreover, Ludewig et al [28] have grown GaAsBi/GaAs MQWs (up to 5 QWs) by MOVPE with good crystalline quality.…”