| 摘要 |
PROBLEM TO BE SOLVED: To provide an HEMT device having a high controllability over threshold voltage, and to provide a semiconductor multilayer structure for realizing the element. SOLUTION: In the HEMT element 20, a p-type semiconductor layer 4 is interposed between channel layers 9 formed of InGaN. By increasing the band of the InGaN which constitutes the second channel layer 5 above the p-type semiconductor layer 4, the threshold voltage can be increased. If the band of the InGaN is increased to the Fermi level, the HEMT element which is pinched off, when the gate bias voltage is 0 V, can be realized. Since doping amount is small, even if the dopant is Mg, memory effect at the forming of a layer by MOCVD can be fully suppressed; and moreover, since the position where the p-type semiconductor layer 4 is formed is away from a hetero interface, diffusion of Mg into an electron supply layer 11 hardly occurs. The p-type dopant concentration is low in a two-dimensional electron gas generated region, hardly causing decline in the electron mobility due to the scattering of the dopant. COPYRIGHT: (C)2006,JPO&NCIPI |
