PROBLEM TO BE SOLVED: To provide a GaN based high mobility transistor in which an i-type GaN layer for forming a two-dimensional electron gas layer has a high electric resistivity and pinch-off state can be realized even when the gate bias voltage is 0 V.;SOLUTION: On a GaN buffer layer 2 formed on a semi-insulating substrate 1, a layer structure of an i-type GaN layer 3 having an electric resistivity not lower than 1×106 Ω/cm2, an i-type AlGaN layer 4 disposed in heterojunction with the i-type GaN layer 3 while forming an undercut part 4a at the i-type GaN layer, and an n-type GaN layer 5 disposed to bury the side part and the undercut part 4a of the i-type AlGaN layer 4 is formed wherein a gate electrode G is formed on the i-type AlGaN layer 4 and a source electrode S and a drain electrode D are formed, respectively, on the n-type GaN layers 5 and 5 thus constituting a GaN based high mobility transistor.;COPYRIGHT: (C)2002,JPO
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