Selective wet etching of AlInN layers for nitride-based MEMS and photonic device structures

Watson, I.M. and Xiong, C. and Gu, E. and Dawson, M.D. and Rizzi, F. and Bejtka, K. and Edwards, P.R. and Martin, R.W. (2008) Selective wet etching of AlInN layers for nitride-based MEMS and photonic device structures. Proceedings of SPIE the International Society for Optical Engineering, 6993. ISSN 0277-786X (https://doi.org/10.1117/12.781881)

Abstract

Processing of GaN-AlInN-GaN epitaxial trilayers into 3-dimensional microstructures, using a combination of vertical dry etching and lateral wet etching, is discussed. The AlInN layers were grown so as to have an InN mole fraction close to the value of 17% required for lattice matching with GaN. Inductively coupled plasma etching with chlorine-argon gas mixtures was used to define mesa features with near-vertical sidewalls. Refluxing aqueous solutions of nitric acid of 2 molar concentration allowed highly selective lateral etching of the AlInN interlayers exposed on the mesa sidewalls, providing a novel sacrificial layer technology for the III-nitride materials. Lateral etch rates of 0.14-0.21 μm/hr were observed for 100-nm AlInN interlayers. Two distinct applications are discussed. In one example, lateral etching of an AlInN layer was used to expose the underside of epitaxial GaN disks for fabrication of planar microcavities. Here, retention of an optically smooth GaN (0001) surface on the underside of the disks is critical. Microbridges with potential for development as sensors were also demonstrated, and the deformation of these structures provides a sensitive probe of the local strain state of the undercut GaN layer.

ORCID iDs

Watson, I.M. ORCID: https://orcid.org/0000-0002-8797-3993

Gu, E. ORCID: https://orcid.org/0000-0002-7607-9902

Dawson, M.D. ORCID: https://orcid.org/0000-0002-6639-2989

Edwards, P.R. ORCID: https://orcid.org/0000-0001-7671-7698

Martin, R.W. ORCID: https://orcid.org/0000-0002-6119-764X

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• Item metadata

  Item type:	Article
  ID code:	14006
  Dates:	Date Event 28 April 2008 Published
  Notes:	Available in: MEMS, MOEMS, and Micromachining III (Proceedings Volume) Proceedings of SPIE Volume: 6993 Editor(s): Hakan Urey Date: 28 May 2008 ISBN: 9780819471918
  Subjects:	Science > Physics > Optics. Light
  Department:	Faculty of Science > Physics > Institute of Photonics Faculty of Science > Physics
  Depositing user:	Miss Lisa Flanagan
  Date deposited:	20 Dec 2009 16:08
  Last modified:	11 Nov 2024 09:07
  URI:	https://strathprints.strath.ac.uk/id/eprint/14006