| 摘要 |
PURPOSE:To enhance the characteristics of a Schottky barrier type field effect transistor SB-FET by forming an active layer on a semi-insulating or high resistance, eptaxial crystal layer, and reducing the effect of impurities which form a deep inpurity level. CONSTITUTION:A non-doped semi-insulating GaAs crystal is obtained by a gaseous phase epitaxial method employing Ga-AsCl3. When said crystal grawth exceeds certain level, impurities (Cr, O) in a substrate is added and the background impurity level shown by a solid line is generated. When the surface is approached, impurity density is lowered as shown by a dot and dash line. TBE in the Figure is the thickness of the non-doped layer wherein the background level is generated. The thickness of the epitaxial layer for the Schottky barrier type FET is set as TBE+TD, where TBE is 0.5-10mum, and TD is 0.2- several mum. TD is the thickness of the region formed by the impurities which are diffused from the substrate to the surface side of the epitaxial layer in the heat treatment for activation after ion implantation. The excellent FET characteristics can be obtained in this way. |
