| 摘要 |
PURPOSE:To increase the face concentration of the secondary electrode gas while holding the high degree of electron movement by a method wherein both surfaces of a thin channel layer are provided with electron supplying layers and the impurity concentration on the electron supplying layer of the substrate side is decreased. CONSTITUTION:Al0.3Ga0.7As layers 11a-11c are provided on a semi-insulating GaAs substrate 21 through the intermediary of a non-dope GaAs buffer layer 22 while the layers 11a and 11c are non-dope but the layer 11b is doped with donor impurity e.g. around 1-5X10<17>(cm<-2>) of Si. Besides, the layers 11b and 11c are respectively made around 20(nm) and 10-20(nm) thick to be the first electron supplying layer. Then an non-dope GaAs channel layer 12 around 10(nm) thick is provided on the layer 11c. Moreover Al0.3Ga0.7As layers 13a, 13b are provided on the layer 12 while the layer 13a is non-dope but the layer 13b is doped with e.g. around 1-2X10<18>(cm<-3>) of Si. On the other hand, the layers 13a and 13b are respectively made 0-10(nm) and e.g. 100(nm) thick. Finally a gate electrode 25, a source electrode 26 and a drain electrode 27 may be provided on this semiconductor substrate. |
