Characterization of trap states in buried nitrogen-implanted β-Ga2O3

Applied Physics Letters, Volume 117, Issue 24, December 2020. The advent of acceptor-type doping of β-Ga2O3 through ion-implantation of nitrogen has opened a new design space for junction-type devices with estimated breakdown voltages in excess of a few kVs. However, the presence of deep states due to intrinsic defects in β-Ga2O3 and implantation damage could be detrimental to the performance and reliability of such devices. We give a phenomenological description and experimental demonstration of the effects of nitrogen implantation in a buried blocking layer on the performance of transistors. The partial activation of acceptor-like states in the buried implanted region has been revealed and estimated to be ∼20% through a junction spectroscopic technique involving substrate-bias and sub-bandgap illumination, which remains elusive to standard characterization techniques. The characterization technique, along with a space-charge model of the channel and band model of the buried implanted layer, has revealed the presence of photosensitive mid-bandgap (∼2.47 eV below the conduction band) and tail states near the valence band edge of nitrogen-implanted β-Ga2O3.