JPS647665A - Compound semiconductor device - Google Patents

Abstract

PURPOSE:To isolate a plurality of elements formed onto a semi-insulating compound semiconductor substrate electrically by forming a conductive layer not electrically connected to an active element just under and around the active element shaped into the substrate and fixing the conductive layer at fixed potential. CONSTITUTION:In a compound semiconductor device in which an active element is shaped into a semi-insulating compound semiconductor substrate 1, conductive layers 9, 8 not electrically connected to the active element are formed just under and around said active element in the compound semiconductor substrate 1, and the conductive layers 9, 8 are fixed at constant potential, thus electrically shielding the insides and outsides of the conductive layers 9, 8 in the compound semiconductor substrate 1. An N channel FET consisting of a source (S), a gate (G) and a drain (D) is shaped onto the substrate 1 such as a semi-insulating GaAs substrate 1, the FET is surrounded completely by the conductive layer 8 such as a P-type side face region 8 formed in specified depth in the periphery and the conductive layer 9 such as a P-type base region 9 shaped to a plate shape just under the FET, and these regions 8, 9 are grounded through an ohmic electrode 10.