Enhanced diffusion as a mechanism for ion-induced damage propagation in GaN

Citation
Ed. Haberer et al., Enhanced diffusion as a mechanism for ion-induced damage propagation in GaN, J VAC SCI B, 19(3), 2001, pp. 603-608
Citations number
25
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science","Material Science & Engineering
Journal title
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B
ISSN journal
1071-1023 → ACNP
Volume
19
Issue
3
Year of publication
2001
Pages
603 - 608
Database
ISI
SICI code
1071-1023(200105/06)19:3<603:EDAAMF>2.0.ZU;2-2
Abstract
Although GaN is a chemically inert, thermally stable material, it has demon strated sensitivity to ion damage generated by dry etch processes such as r eacting ion etching and inductively coupled plasma etching. Recombination-e nhanced diffusion is an important mechanism which has been observed in othe r m-V semiconductor systems. In this study we examine the possibility of en hanced diffusion in GaN using quantum well (QW) probe structures. The deepe r QWs (750 and 1000 Angstrom deep) showed a steady decrease in relative pho toluminescence (PL) intensity with time, providing evidence of the cooperat ive effects of channeling and defect diffusion in deep etch damage propagat ion in GaN. In contrast, shallow QWs (150 and 250 Angstrom from the surface ) showed a slight decrease followed by a gradual increase in relative PL in tensity with; time which was explained by defect annihilation. Exposure to above band gap illumination, used to simulate and enhance carrier generatio n during etch, appears to speed defect annihilation in high defect concentr ation regions resulting in an increase in QW luminescence, where as in lowe r defect concentration areas, above band gap illumination does not appear t o significantly alter QW luminescence. We attribute this;difference in beha vior to a difference in diffusion constant. The diffusion constant in less damaged regions may be much lower than that of the highly damaged material. (C) 2001 American Vacuum Society.