Defects Created by 25 keV Hydrogen Implantation in n-type GaN

Abstract

We have studied defects introduced in n-GaN during 25 keV hydrogen and 40 keV He implantation using deep level transient spectroscopy (DLTS). These measurements revealed that 25 keV hydrogen implantation introduces a complex set of electron traps, of which most are different to the defects observed after high-energy (MeV) electron and proton implantation. At least three of the defects detected after 25 keV proton implantation exhibit a metastable character in that they can be reproducibly removed and re-introduced during reverse and zero bias anneal cycles. Isochronal and isothermal annealing experiments yielded low activation energies of approximately 0.1 -0.2 eV for both processes. By comparison, 40 keV He ion implantation introduced the same metastable defects, but in different relative concentrations.