| 摘要 |
PURPOSE:To improve the high-speed and high-frequency characteristics with a large degree of freedom in design of the titled device by a method wherein the first semiconductor layer of high purity, second semiconductor layer having a smaller electron affinity than this first semiconductor, and third semiconductor layer with increasing electron affinity are successively laminated on a high- resistant substrate. CONSTITUTION:The titled device is composed of the first semiconductor layer 12 of high purity or P-type, second semiconductor layer 13 having a smaller electron affinity than the semiconductor layer 12 and an N-type, high impurity concentration, and third semiconductor layer 14 with upward-increasing electron affinity and partly impurity-doped to N-type. Then, the surface electron density of an electron channel is controlled by the total donor density of the N-doped second semiconductor layer and the third semiconductor layer, and the gate input capacitance is controlled by the thickness of the third semiconductor layer of high purity. |
