Passivation efficacy study of Al2O3dielectric on self-catalyzed molecular beam epitaxially grown GaAs1- xSb x nanowires

Mehul Parakh; Priyanka Ramaswamy; Shisir Devkota; Hirandeep Kuchoor; Kendall Dawkins; Shanthi Iyer

doi:10.1088/1361-6528/ac69f8

Passivation efficacy study of Al₂O₃dielectric on self-catalyzed molecular beam epitaxially grown GaAs_{1- x}Sb _x nanowires

Nanotechnology. 2022 May 11;33(31). doi: 10.1088/1361-6528/ac69f8.

Authors

Mehul Parakh¹, Priyanka Ramaswamy², Shisir Devkota¹, Hirandeep Kuchoor¹, Kendall Dawkins¹, Shanthi Iyer¹

Affiliations

¹ Nanoengineering, Joint School of Nanoscience and Nanoengineering, North Carolina A&T State University, Greensboro NC, 27401, United States of Americ a.
² Department of Electrical and Computer Engineering, North Carolina A&T State University, Greensboro NC, 27411, United States of America.

PMID: 35468592
DOI: 10.1088/1361-6528/ac69f8

Abstract

This work evaluates the passivation efficacy of thermal atomic layer deposited (ALD) Al₂O₃dielectric layer on self-catalyzed GaAs_1-xSb_xnanowires (NWs) grown using molecular beam epitaxy. A detailed assessment of surface chemical composition and optical properties of Al₂O₃passivated NWs with and without prior sulfur treatment were studied and compared to as-grown samples using x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and low-temperature photoluminescence (PL) spectroscopy. The XPS measurements reveal that prior sulfur treatment followed by Al₂O₃ALD deposition abates III-V native oxides from the NW surface. However, the degradation in 4K-PL intensity by an order of magnitude observed for NWs with Al₂O₃shell layer compared to the as-grown NWs, irrespective of prior sulfur treatment, suggests the formation of defect states at the NW/dielectric interface contributing to non-radiative recombination centers. This is corroborated by the Raman spectral broadening of LO and TO Raman modes, increased background scattering, and redshift observed for Al₂O₃deposited NWs relative to the as-grown. Thus, our work seems to indicate the unsuitability of ALD deposited Al₂O₃as a passivation layer for GaAsSb NWs.

Keywords: Al2O3 passivation; GaAs1-x Sb x nanowires (NWs); atomic layer deposition (ALD); dielectric/III–V nanowire interface; molecular beam epitaxy (MBE).