| 摘要 |
PURPOSE:To obtain the titled which can simultaneously control the threshold voltages of a normally-on type FET and a normally-off type FET, by a method wherein the longitudinal directions of respective channels of the normally-on type FET and the normally-off type FET are made as different specific crystal- axial directions. CONSTITUTION:On a 100GaAs semi-insulation substrate 1, ohmic regions 3 serving as the source-drain regions of a FET are formed so that the channel longitudinal direction may be the same as the direction of a crystal axis 011<->, and a channel region 2 is formed by sandwiching both ohmic regions. On the other hand, ohmic regions 3 and a channel region 2' similar to said case are formed also in the same as the direction of a crystal axis 01<-1>1<-> in the channel longitudinal direction. In this case, the channel regions 2, 2' formed in the directions of 011<-> and 01<->1 are formed by an ion implantation and a heat treatment, and the coefficients of impurity diffusion in the 011<-> direction and the 01<->1 direction are larger in the 01<->1<-> direction by a factor of about 4 than in the 011<-> direction. Thereby, the impurity concentration of the channel region 2' is higher than that of the 011<-> directional channel region 2 by a factor of about 2. |
