Atomically resolved study of the unpinned GaN ( 10 1 ¯ 0 ) surface by cross-sectional scanning tunneling microscopy

E. G. Banfi; T. J. F. Verstijnen; E. Monroy; M. E. Flatté; P. M. Koenraad

doi:10.1103/PhysRevB.108.085304

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Atomically resolved study of the unpinned GaN ( 10 1 ¯ 0 ) surface by cross-sectional scanning tunneling microscopy

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Atomically resolved study of the unpinned GaN ( 10 1 ¯ 0 ) surface by cross-sectional scanning tunneling microscopy

E. G. Banfi, T. J. F. Verstijnen, E. Monroy, M. E. Flatté and P. M. Koenraad

Physical review. B, Vol.108(8), 085304

08/2023

DOI: 10.1103/PhysRevB.108.085304

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Abstract

Gallium nitride has been studied thoroughly in recent decades as the material is relevant for applications in blue-light-emitting devices and laser diodes, as well as high-power and high-frequency transistors. This material has rarely been explored by cross-sectional scanning tunneling microscopy (X-STM), in spite of the relevance of its m plane, which constitutes the output facet of commercial lasers and the sidewalls of GaN nanowires, and has been intensively explored as an alternative orientation for light emitters due to its nonpolar nature. Here we successfully investigate a clean m plane of wurtzite GaN and study the presence of gallium vacancies by X-STM at liquid nitrogen temperature. We observe Friedel oscillations around the defects and characterize the dependence of the oscillation radius on the applied bias. This physical phenomenon, combined with the tunneling conditions, clarifies the charge state of the vacancy and the origin of the free carriers in GaN that screen the Ga vacancies. We observe a predicted bi-stability of the N atom neighboring the Ga vacancy and perform density functional theory calculations to complement the experimental results. We obtain high-quality clean cleavages on the GaN m plane, which will allow for the study of other nanostructured GaN-based materials and devices

Details

Title: Subtitle: Atomically resolved study of the unpinned GaN ( 10 1 ¯ 0 ) surface by cross-sectional scanning tunneling microscopy
Creators: E. G. Banfi - Eindhoven University of Technology
T. J. F. Verstijnen - Eindhoven University of Technology
E. Monroy - CEA Grenoble
M. E. Flatté - University of Iowa
P. M. Koenraad - Eindhoven University of Technology
Resource Type: Journal article
Publication Details: Physical review. B, Vol.108(8), 085304
DOI: 10.1103/PhysRevB.108.085304
ISSN: 2469-9950
eISSN: 2469-9969
Grant note: DOI: 10.13039/501100003246, name: Nederlandse Organisatie voor Wetenschappelijk Onderzoek, award: 10018478, EINF-3528; DOI: 10.13039/100000181, name: Air Force Office of Scientific Research, award: FA9550-22-1-0308
Language: English
Date published: 08/2023
Academic Unit: Electrical and Computer Engineering; Physics and Astronomy
Record Identifier: 9984455614602771

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