Ion-beam-induced reconstruction of amorphous GaN - art. no. 113202

Wurtzite GaN can be rendered amorphous by high-dose heavy-ion bombardment. We show here that relatively low-dose reirradiation of such amorphous GaN ( a-GaN) with MeV light ions can significantly change some of the physical pr operties of a-GaN. In particular, light-ion reirradiation of a-GaN results in (i) an increase in material density, (ii) the suppression of complete de composition during postimplantation annealing, (iii) a significant increase in the values of hardness and Young's modulus, and (iv) an apparent decrea se in the absorption of visible light. Transmission electronmicroscopy show s that a-GaN remains completely amorphous after light-ion reirradiation. Th erefore, we attribute the above effects of light-ion reirradiation to an io n-beam-induced atomic-level reconstruction of the amorphous phase. Results indicate that electronic energy loss of light ions is responsible for the c hanges in the mechanical properties and for the suppression of thermally in duced decomposition of a-GaN. However, the changes in the density of a-GaN appear to be controlled by the nuclear energy loss of light ions.