Talk abstract

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.