Molecular beam epitaxy and properties of GaAsBi/GaAs quantum wells grown by molecular beam epitaxy: effect of thermal an
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NANO EXPRESS
Open Access
Molecular beam epitaxy and properties of GaAsBi/GaAs quantum wells grown by molecular beam epitaxy: effect of thermal annealing Hajer Makhloufi1,2,6, Poonyasiri Boonpeng1,2,6, Simone Mazzucato3,6, Julien Nicolai4,6, Alexandre Arnoult1,6, Teresa Hungria5,6, Guy Lacoste1,6, Christophe Gatel4,6, Anne Ponchet4,6, Hélène Carrère3,6, Xavier Marie3,6 and Chantal Fontaine1,6*
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. Keywords: Dilute bismides; Molecular beam epitaxy; Heteroepitaxy; X-ray diffraction; Transmission electron microscopy; Photoluminescence
Background Dilute bismuth alloys grown on GaAs attract more and more attention because of their peculiar electronic properties. Adding bismuth to GaAs efficiently decreases the gap energy of this semiconductor [1] through a change in its valence band properties and increases the spin-orbit interaction [2]. GaAsBi/GaAs quantum wells (QWs) are of interest with a view to fabricate laser diodes which could benefit from these properties, in particular from the higher spin-orbit splitting expected to lower the non-radiative carrier recombination due to Auger mechanisms [3]. Moreover, their emitting wavelength range could meet the requirements for infrared GaAs-based laser diodes as an alternative to low-temperature GaInAs/GaAs [4] and GaInAsN/GaAs [5] QWs. Besides, the properties of these III-V alloys are also very promising for photovoltaics [6]. Up to now, literature on GaAsBi has mainly been devoted to thick layers (see [7] and ref. herein), and only a few papers on the growth of quantum * Correspondence: [email protected] 1 CNRS, LAAS, 7, avenue du Colonel Roche, Toulouse 31400, France 6 Université de Toulouse, Toulouse 31400, France Full list of author information is available at the end of the article
well structures have been published [8]. Here, we present the structural and optical properties of a GaAsBi/GaAs QW grown by molecular beam epitaxy (MBE) and discuss their change after rapid thermal annealing (RTA).
Methods GaAsBi quantum well structures were grown using a 32P RIBER (Bezons, France) MBE system. Substrates were pieces of a semi-insulating GaAs substrate soldered with indium on a silicon wafer mounted on the substrate holder to be loaded in the MBE system. The substrate thermocouple temperature for the molybdenum substrate holder was first calibrated by using a band ed
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