| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor device which is a nitride hetero field effect transistor having the character of an enhancement type field effect transistor. SOLUTION: Near the surface of the semiconductor of the nitride hetero field effect transistor, a thin-layer channel layer semiconductor layer 2 is arranged as interposed between an upper barrier layer semiconductor layer 1 and a lower barrier layer semiconductor layer 3. In the lower barrier layer semiconductor layer 3, a composition gradient (which means that the composition of a semiconductor constituting a layer monotonously changes in the thickness direction of the layer) is formed. The lower barrier layer semiconductor layer 3 and an inner small band gap semiconductor layer 4 are connected below the lower barrier layer semiconductor layer 3 without the discontinuity of the compositions. COPYRIGHT: (C)2006,JPO&NCIPI
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