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Doping Issues in Wide Band-Gap Semiconductors

Exeter, United Kingdom
21-23 March 2001
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Talk abstract

Problems of doping GaN by ion implantation

S. O. Kucheyev

Department of Electronic Materials Engineering, RSPhysSE, The

J. S. Williams (1), C. Jagadish (1), J. Zou (2), G. Li (3), J. E. Bradby (1), and H. Boudinov (1)

(1) Department of Electronic Materials Engineering, RSPhysSE, The Australian National, University, Canberra, Australia, (2) Australian Key Center for Microscopy and Microanalysis, The University of Sydney, Sydney, NSW 2006, Australia, (3) Ledex Corp., No. 9, Ta-Yio 1st St., Ta-Fa Industrial District, Kaohsiung County, Taiwan

In the fabrication of GaN-based devices, ion implantation represents a very attractive processing tool for several technological steps such as selective-area doping, dry etching, and electrical isolation. However, lattice disorder is always a concomitant (and often undesirable) effect of ion bombardment. Our recent studies have revealed that, unlike the situation for mature semiconductors such as Si and GaAs, GaN exhibits a range of intriguing behavior involving extreme property changes under ion bombardment. In this presentation, we discuss opportunities and highlight current problems, associated with implantation disorder, which may hinder a successful application of ion implantation in the fabrication of GaN-based devices. In particular, the following problems will be discussed: (i) a complex and somewhat unexpected damage buildup behavior; (ii) preferential loss of nitrogen from the GaN surface during bombardment; (iii) formation of extended defects which appear to be difficult (or even impossible) to anneal; (iv) ion-beam-induced porosity due to material dissociation with the formation of nitrogen gas bubbles; (v) anomalous surface erosion during ion bombardment at elevated temperatures; (vi) a dramatic effect of implantation disorder on mechanical properties, affecting contact damage; and (vii) current problems with annealing of amorphous GaN. Emphasis is given to understanding physical mechanisms responsible for such a somewhat extreme behavior of GaN under ion bombardment.