Patent ID: 6194747
Filing Date: 2001-02-27
Classification: H01L

Abstract:
A field effect transistor, comprising, upon an InP substrate:a channel layer formed from an undoped semiconductor,an electron supply layer in which n-type impurities are doped partially or all along the direction of the thickness, for supplying carriers to said channel layer,an undoped InAlAs Schottky layer,an n-type InAlAs first cap layer set in contact with said Schottky layer,an n-type InGaAs second cap layer set in contact with said first cap layer,a first recess opening bored through said second cap layer to the upper surface of said first cap layer, the upper surface of said first cap layer defining the bottom of said first recess opening,a second recess opening which is bored, within the first recess opening, through said first cap layer to the upper surface of said Schottky layer or to the interior of said Schottky layer by removing a part thereof, wherein the width of the top of said second recess opening is smaller than the width of the bottom of said first recess opening,a gate electrode formed on the exposed surface of said Schottky layer at the bottom of the second recess opening, anda source electrode and a drain electrode which are formed upon said second cap layer on each side of said first recess opening.