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The role of surface roughness on dislocation bending and stress evolution in low mobility AlGaN films during growth

Bardhan, Abheek and Mohan, Nagaboopathy and Chandrasekar, Hareesh and Ghosh, Priyadarshini and Rao, D V Sridhara and Raghavan, Srinivasan (2018) The role of surface roughness on dislocation bending and stress evolution in low mobility AlGaN films during growth. In: JOURNAL OF APPLIED PHYSICS, 123 (16).

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Official URL: http://dx.doi.org/ 10.1063/1.5005080

Abstract

The bending and interaction of threading dislocations are essential to reduce their density for applications involving III-nitrides. Bending of dislocation lines also relaxes the compressive growth stress that is essential to prevent cracking on cooling down due to tensile thermal expansion mismatch stress while growing on Si substrates. It is shown in this work that surface roughness plays a key role in dislocation bending. Dislocations only bend and relax compressive stresses when the lines intersect a smooth surface. These films then crack. In rough films, dislocation lines which terminate at the bottom of the valleys remain straight. Compressive stresses are not relaxed and the films are relatively crack-free. The reasons for this difference are discussed in this work along with the implications on simultaneously meeting the requirements of films being smooth, crack free and having low defect density for device applications. Published by AIP Publishing.

Item Type: Journal Article
Additional Information: Copy right for this article belong to AMER INST PHYSICS, 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA
Department/Centre: Division of Chemical Sciences > Materials Research Centre
Division of Interdisciplinary Research > Centre for Nano Science and Engineering
Depositing User: Id for Latest eprints
Date Deposited: 23 May 2018 14:54
Last Modified: 23 May 2018 14:54
URI: http://eprints.iisc.ac.in/id/eprint/59923

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