| 摘要 |
PURPOSE:To provide a field effect transistor which efficiently operates at a low current, a low voltage and a small noise. CONSTITUTION:In a field effect transistor, an undope channel layer 3 and a barrier layer 16 with a band gap larger than the channel layer 3 are formed on a substrate 1, and the barrier layer 16 has at least two atomic layer doping layers, and the layer 7 with the highest concentration among their layers is separated from the channel layer 3 by at least, 7nm, and a doping concentration of at least one layer is at least 5X10<12> particles/cm<2>. Thus, since a mobility of a channel does not depend on the concentration of an atomic layer doping 2, the distance from a gate electrode to the channel can be decreased without reducing the mobility. |
