Schottky contact and the thermal stability of Ni on n-type GaN

Abstract

The Schottky barrier height of Ni on n-GaN has been measured to be 0.56 and 0.66 eV by capacitance–voltage (C–V) and current–density–temperature (J–T) methods, respectively. Gallium nickel (Ga4Ni3) is formed as Ni is deposited on the GaN film, which affects the barrier height markedly. The thermal stability of Ni on GaN is also investigated by annealing these specimens at various temperatures. Specimen annealing at temperatures above 200 °C leads to the formation of nickel nitrides Ni3N and Ni4N at the interface of Ni and GaN. These interfacial compounds change the measured barrier height to 1.0 and 0.8 eV by C–V and J–T methods, respectively. Comparisons of Schottky characteristics of Ni with those of Pt, Pd, Au, and Ti are also discussed.

Solar-blind MSM-photodetectors based on Al x Ga1-x N heterostructures

“…The work function of Ni is higher than that of Mo, but the Schottky barrier height is lower. This is because the Schottky behavior is significantly affected by interfacial interactions between the Ni films and semiconductor surface (Guo et al 1996). NiAu contacts were deposited on Al 0.2 Ga 0.8 N /GaN two-dimensional electron gas structure for the fabrication of MSM-UV photodetectors with estimated Schottky barrier height of 0.97 eV (Su et al 2005)-in good agreement with our result.…”

Center for the Radiation Studies and Solutions

“…In previous studies, the non-ideal electrical characteristics of as-fabricated GaN Schottky diodes and, in particular, the scatter in the reported barrier height of Ni/GaN contacts, have been are proposed to be attributable to surface-states and interfacial defects, dislocation-related current paths, interfacial layers induced by metal/GaN reactions or surface preparation, and material non-uniformity and quality [28,[32][33][34][35][36][37][38][39][40]. While a combination of the above is also likely to have an effect on the present samples, effects associated with dislocations and interfacial defect states are of particular relevance to this study because irradiation and/or post-irradiation annealing are likely to have a significant influence on device characteristics.…”

“…While such discrepancies are not surprising in view of the non-idealities reported in most studies of metal/n-GaN Schottky barrier diodes [28][29][30][31], in the present study the difference in I-V and C-V extracted barrier heights is primarily due to radiation-induced changes. For example, and as shown in Fig.2, (j>g was found to increase from 1.14±0.02 to 1.30±0.01 eV after a cumulative gamma-ray dose of 21 Mrad(Si), whereas <j>% 0 remained essentially constant with irradiation exposure [15].In previous studies, the non-ideal electrical characteristics of as-fabricated GaN Schottky diodes and, in particular, the scatter in the reported barrier height of Ni/GaN contacts, have been are proposed to be attributable to surface-states and interfacial defects, dislocation-related current paths, interfacial layers induced by metal/GaN reactions or surface preparation, and material non-uniformity and quality [28,[32][33][34][35][36][37][38][39][40]. While a combination of the above is also likely to have an effect on the present samples, effects associated with dislocations and interfacial defect states are of particular relevance to this study because irradiation and/or post-irradiation annealing are likely to have a significant influence on device characteristics.…”

Metal contacts on ZnSe and GaN

“…(Guo et al, 1996b) They found that a Ni3Gas phase was formed at the interface during deposition and that Ni,N phases were formed after annealing at 200°C. They determined the presence of these phases by x-ray deaction (XRD), however their interpretation of the XRD peaks was flawed.…”