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Method for inferring the mechanical strain of GaN-on-Si epitaxial layers using optical profilometry and finite element analysis

B. F. Spiridon, M. Toon, A. Hinz, Saptarsi Ghosh Orcid Logo, S. M. Fairclough, B. J. E. Guilhabert Orcid Logo, M. J. Strain Orcid Logo, I. M. Watson, M. D. Dawson Orcid Logo, D. J. Wallis, R. A. Oliver

Optical Materials Express, Volume: 11, Issue: 6, Start page: 1643

Swansea University Author: Saptarsi Ghosh Orcid Logo

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DOI (Published version): 10.1364/ome.418728

Abstract

GaN-on-Si has become a useful fabrication route for many GaN devices and applications, but the mechanical stress incorporated throughout the material stack can impact the viability of this approach. The transfer printing of GaN membrane devices, a promising emerging technology, is most effective wit...

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Published in: Optical Materials Express
ISSN: 2159-3930
Published: Optica Publishing Group 2021
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa66875
Abstract: GaN-on-Si has become a useful fabrication route for many GaN devices and applications, but the mechanical stress incorporated throughout the material stack can impact the viability of this approach. The transfer printing of GaN membrane devices, a promising emerging technology, is most effective with flat membranes, but in practice many GaN structures released from their Si substrate are highly bowed due to the strain in the epitaxial nitride stack. Our approach uses the optical profiles of epitaxial wafers and membranes as inputs for inferring the mechanical strain state of the material by multi-variable numerical model fitting using COMSOL Multiphysics. This versatile, adaptable and scalable method was tested on samples from two GaN-on-Si wafers, revealing the relationship between built-in strain and material bow in principal-component fashion, returning 3–4×10−4 strain estimates for the AlGaN (compressive) and GaN (tensile) layers, and suggesting the occurrence of plastic deformation during transfer printing.
College: Faculty of Science and Engineering
Issue: 6
Start Page: 1643

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