| 摘要 |
PURPOSE:To reduce the decrease in electron mobility by a method wherein the concentration of an electron accumulation layer generated in the channel layer located in the lower part of a gate electrode is easily controlled, and the spread of electron distribution is inhibited. CONSTITUTION:A GaAs single crystal 22 undoped with impurities is grown on a semi-insulation GaAs substrate 21, and an AlXGa1-XAs layer 23 undoped with impurities is grown thereon as the buffer layer. Further, an electron supply layer 24 is grown thereon under continuous variation in concentration of Si which serves as the impurity, and a control electrode 26 is formed thereon. Source and drain electrodes 27 and 28 that are input-output electrodes are formed by evaporation of AuGb/Ni. The electron mobility improves by a factor of several times, as compared with the conventional case of a constant impurity concentration of the layer 24, by thus decreasing said impurity concentration with the distance from the layer 23. |
