X-ray photoelectron spectroscopy study on effects of ultra-high-pressure annealing on surface of Mg-ion-implanted GaN

Abstract

The effects of ultra-high-pressure annealing (UHPA) on the surface of Mg-ion-implanted GaN were investigated by X-ray photoelectron spectroscopy (XPS). After Mg ion implantation or Mg–N co-implantation, GaN was annealed at 1400 °C for 5 min under a nitrogen pressure of 1 GPa. No deterioration of the surface stoichiometry occurred after UHPA despite the extremely high annealing temperature. The angle-resolved XPS with calibration showed that the surface Fermi level was pinned at 0.5 eV from the conduction band edge after dehydrogenation subsequent to UHPA. However, the absence of pinning at the charge neutrality level showed that surface disorder was absent after UHPA. The surface photovoltaic effect as evidence of the achievement of p-type conduction even in the near-surface region was more remarkable for Mg–N-ion-implanted samples after dehydrogenation subsequent to UHPA. There is the possibility that the density of N-vacancy-related defects was reduced more by Mg–N co-implantation.

Effect of annealing time and pressure on electrical activation and surface morphology of Mg-implanted GaN annealed at 1300 °C in ultra-high-pressure nitrogen ambient

“…15) In our previous study, we used ultra-highpressure annealing (UHPA) which was carried out under an ultra-high-pressure nitrogen gas with GaN powder (source of Ga pressure) to suppress thermal decomposition. [16][17][18][19] This technique enables us to increase annealing temperature as well as extend annealing time. We demonstrated high activation of implanted Mg as well as a low compensation ratio, using annealing at 1400 °C for 5 min in a 1 GPa nitrogen ambient.…”

Investigation of gap states near conduction band edge in vicinity of interface between Mg-ion-implanted GaN and Al2O3 deposited after ultra-high-pressure annealing

“…X-ray photoelectron spectroscopy also provided information on the surface after UHPA at 1400 °C, which indicated the absence of nitrogen deficits at the annealed surface. 31) Moreover, the electric properties of GaN MOS structures formed after UHPA have been reported for heavily Mg-implanted and nonimplanted samples. 32) However, effects of post-implantation UHPA on the electrical states, i.e.…”

Investigation of dominance in near-surface region on electrical properties of AlGaN/GaN heterostructures using TLM, XPS, and PEC etching techniques

“…Using Sample A as an example, let us derive the location of E FS from the Ga 3d and valence band spectra obtained from XPS measurements. The E FS position relative to the valence band maximum (VBM), E V , can be derived as 17,18) ( ) ( ) ()…”