| 摘要 |
PURPOSE:To improve the integration density of a device and decrease the effect of carrier accumulation by a method wherein a reverse conductivity type layer of low density is adjacent to base layers, and the density is enhanced relatively on the base side and more enhanced particularly on the surface side. CONSTITUTION:An N<--> or I-layer 113 and an N<-> layer 13 are epitaxial-grown on an N<+> Si substrate 11, then an SiO2 film 121 is opened, thus P-layers 14 reaching the layer 113 are formed, and a P-base 114 and an N<+> drain (or a source) 12 are formed at a fixed position. Electrode 2 and 4 are provided, and an electrode 1 is added to the substrate 11. By this constitution, since the base 114 is adjacent to a layer of relatively high density, it becomes difficult to inject minority carriers, and easy to decrease the potential barrier of the base layer. Therefore, off-current increases to a some degree, but when the base voltage is impressed, conversion conductance can be enhanced, and accordingly on-resistance can be reduced. In the presence of the N<-> layer 13, the electric field becomes steep, an efficient base width can be reduced, and consequently the operational speed is improved, thus the integration degree is also improved. |
