Dislocation bending and stress evolution in Mg-doped GaN films on Si substrates

Soman, Rohith and Mohan, Nagaboopathy and Chandrasekar, Hareesh and Bhat, Navakanta and Raghavan, Srinivasan (2018) Dislocation bending and stress evolution in Mg-doped GaN films on Si substrates. In: JOURNAL OF APPLIED PHYSICS, 124 (24).

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Abstract

P-type doping using Mg is essential for realizing a variety of electronic and optoelectronic III-nitride devices involving hetero-epitaxial thin films that also contain a significant number of dislocations. We report on the effect of Mg incorporation on dislocation and stress evolution during the growth of GaN thin films by using in situ curvature measurements and ex situ transmission electron microscopy. A complete picture involving the interplay between three effects-dopant size effect, dislocation bending, and polarity inversion is presented. Mg aids dislocation bending, which in turn generates tensile stresses in Mg-doped GaN films As a result, the compressive stress expected due to the dopant size difference effect can only be discerned clearly in films with dislocation densities below 5 x 109 cm(-2). Polarity inversion at doping exceeding 1019 cm(-3) is associated with a sharp drop in screw dislocation density. A kinetic stress evolution model has been developed to capture dislocation bending and size difference effects, and a match between calculated bending angle from the model and that measured from TEM images is obtained. Published by AIP Publishing.

Item Type:	Journal Article
Publication:	JOURNAL OF APPLIED PHYSICS
Publisher:	AMER INST PHYSICS
Additional Information:	Copyright of this article belongs to AMER INST PHYSICS
Department/Centre:	Division of Chemical Sciences > Materials Research Centre Division of Electrical Sciences > Electrical Communication Engineering Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited:	29 Jan 2019 08:55
Last Modified:	29 Jan 2019 08:55
URI:	http://eprints.iisc.ac.in/id/eprint/61537

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