Al_xGa_<1-x>N/GaN HFETゲート構造における表面・界面電子特性の評価と制御

概要

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We investigated electronic properties of Al_xGa_<1-x>N/GaN gate structures using a thin anodic Al_2O_3 layer and Ni metal, and the influence of surface preparation or thermal annealing of bare i-AlGaN/GaN heterostructures on channel electrons (2DEG). Ni/anodic-Al_2O_3/i-AlGaN/GaN structures effectively suppressed the reverse-biased gate leakage current down to 10^<-6>A/cm^2range, after optimum annealing in N_2 at 400℃. Hall effect measurements of the bare i-AlGaN/GaN sample revealed that 2DEG density at i-AlGaN/GaN interface is considerably affected by the surface preparation condition. Furthermore, a high temperature annealing in O_2 ambient led to increase of 2DEG density together with considerable decrease of the electron mobility, suggesting enhanced incorporation of oxygen in AlGaN layers.
北海道工業大学の論文
2007-03-26