| 摘要 |
<p>A normally off-type high electron mobility transistor (HEMT) has: a first single crystalline semiconductor layer (12), such as an undoped GaAs layer; a second single crystalline semiconductor layer (13), such as an N-doped AlGaAs layer, having an electron affinity different from that of the first single crystalline semiconductor layer (12); a heterojunction (14) between the first and second single crystalline semiconductor layers; an electron-storing layer (18) serving as a conduction channel (19) formed in proximity to the heterojunction (18); and a gate electrode (16) for controlling the concentration of quasi two-dimensional electron gas (5) in the conduction channel. According to the present invention, and additional semiconductor layer (17), such as an N-doped GaAs layer, is formed at least on part of the second single crystalline layer (13) in the neighbourhood (17A min ) of the gate electrode (16). </p> |
