Tailoring of GaAs/GaAsSb core-shell structured nanowires for IR photodetector applications

Abstract

Ga assisted GaAs/GaAsSb core-shell structured nanowires were successfully grown on chemically etched p-type Si(111) substrate by molecular beam epitaxy (MBE). The morphology, structural and optical properties of the nanowires are found to be strongly influenced by the shell growth temperature and Sb% in the nanowires. The nanowires exhibit planar defects like twins and stacking faults, with more stacking faults and micro-twins found at the top section. Optical characteristics of the nanowires as measured by 4K photoluminescence (PL) exhibit a red shift to 1.2 eV with increasing Sb incorporation up to 12%. The Raman spectra of reference GaAs nanowires show TO and LO modes representative of the zinc blende structure at 291 cm -1 and 267.8 cm -1 , respectively. Red shifts of both modes in conjunction with corresponding asymmetrical peak broadening observed in X-ray diffraction with increasing Sb incorporation are attributed to enhanced strain and disorder within the nanostructures. Nanowires of similar Sb composition but grown at different shell temperatures reveal straight nanowires with better microstructural and optical quality when grown at higher growth temperatures. The presence of GaAs passivation layer significantly enhanced the PL intensity such that PL was observed even at room temperature.

Selective-Area MOCVD Growth and Carrier-Transport-Type Control of InAs(Sb)/GaSb Core–Shell Nanowires

“…In particular, the InAs 1– x Sb x nanowires with Sb content of 9.4% display a perfect ZB structure that is completely free of SFs and TPs. In addition, the distribution of defect density along the InAs­(Sb) nanowires is quite uniform (see Figure S7), which is different from the results obtained in some types of GaAs nanowires grown by MBE where the defects are dominated in the top regions. , The main reason could be the difference in the nanowire growth kinetics between the MOCVD and MBE systems. Other explanations may be related with the difference in the diffusion length of the III adatoms under different growth conditions, the change in temperature, and effective local V/III ratio along the nanowire in the MBE system.…”

Epitaxial High-Yield Intrinsic and Te-Doped Dilute Nitride GaAsSbN Nanowire Heterostructure and Ensemble Photodetector Application

“…A relatively higher Sb concentration was observed in the top segment. Temperaturedependent antimony incorporation 20 and/or self-induced compositional gradient 21 is likely responsible for this subtle compositional fluctuation.…”

A Study of GaAs1–xSbx Axial Nanowires Grown on Monolayer Graphene by Ga-Assisted Molecular Beam Epitaxy for Flexible Near-Infrared Photodetectors

“…Such large red-shifts with a change in V/III BEP ratios are not observed when the NWs are grown on a Si substrate . The Sb composition based on the literature data for thin films indicates a variation from 5.4 to 6.5 at. % for varying the V/III BEP ratio from 15 to 20 for simultaneous opening of the shutters, while it shows a larger variation from 1.2 to 7.5 at.…”