Patent ID: 8120066

Claim:
A single voltage supply pseudomorphic high electron mobility transistor (PHEMT) power device ( 1 ; 1 ′; 1 ″) including: a semi-insulating substrate ( 2 ); an epitaxial substrate ( 3 ) formed on the semi-insulating substrate ( 2 ); the epitaxial substrate ( 3 ) including a buffer layer ( 10 ), a superlattice layer ( 11 ), a first electron supply layer ( 12 , 13 ), a first spacer layer ( 14 ), an electron transit layer ( 15 ), a second spacer layer ( 16 ), a second electron supply layer ( 17 ), a Schottky layer ( 18 ), and a contact layer ( 19 ) sequentially stacked on the semi-insulating substrate ( 2 ); source and drain electrodes ( 4 , 5 ) formed on, and in ohmic contact with the contact layer ( 19 ); and a gate electrode ( 6 ) formed on the Schottky layer ( 18 ) to extend through the contact layer ( 19 ); wherein the gate and source electrodes ( 4 , 6 ) are intended to be grounded, and the drain electrode ( 5 ) is intended to be connected to a voltage supply; the PHEMT power device ( 1 ) being characterized in that the contact layer ( 19 ) includes: a lightly doped contact layer ( 20 ) formed on the Schottky layer ( 18 ); a highly doped contact layer ( 21 ) formed on the lightly doped contact layer ( 20 ) and having a doping concentration higher than the lightly doped contact layer ( 20 ); the PHEMT power device ( 1 ) being further characterized by: a wide recess ( 23 ) formed to penetrate the highly doped contact layer ( 21 ) so as to expose a surface of the lightly doped contact layer ( 20 ); and a narrow recess ( 24 ) formed in the wide recess ( 23 ) to penetrate the lightly doped contact layer ( 20 ) so as to expose a surface of the Schottky layer ( 18 ); wherein the gate electrode ( 6 ) is formed in the narrow recess ( 24 ) and in Schottky contact with the Schottky layer ( 18 ) to extend from the exposed surface of the Schottky layer ( 18 ) through the lightly and highly doped contact layers ( 20 , 21 ); and the source and drain electrodes ( 4 , 5 ) are formed on, and in ohmic contact with the highly doped contact layer ( 21 ) outside the wide recess ( 23 ) so that the wide recess ( 23 ) is arranged between the source and drain electrodes ( 4 , 5 ).