Recessed gate field effect transistor

A semiconductor device comprising:

• a compound semiconductor body having a surface and a recess at the surface, the recess having a bottom and a hollow in the center of the bottom;
• and
• a refractory metal gate electrode having a lower portion disposed within the hollow, the compound semiconductor body comprising:
• a compound semiconductor structure having a surface;
• a channel layer comprising a compound semiconductor of a first conductivity type, containing a dopant impurity, and having a dopant impurity concentration, the channel layer being located at a region of the surface of the compound semiconductor substrate directly between the gate electrode and the compound semiconductor substrate;
• first active layers comprising the compound semiconductor, of first conductivity type, containing the dopant impurity, and having a dopant impurity concentration, the first active layers being located on regions of the surface of the compound semiconductor substrate in the recess where the channel layer is not present;
• and
• second active layers comprising the compound semiconductor, of the first conductivity type, containing the dopant impurity, and having a dopant impurity concentration, the second active layers being located on regions of the surface of the compound semiconductor substrate sandwiching the recess, wherein the compound semiconductor body further comprises a first compound semiconductor layer having a second conductivity type, opposite the first conductivity type, containing a dopant impurity, and having a dopant impurity concentration, the first compound semiconductor layer being disposed on a side of the channel layer and the first active layers opposite a side where the refractory metal gate electrode is located.

A semiconductor device comprising:

• a compound semiconductor body having a surface and a recess at the surface, the recess having a bottom and a hollow in the center of the bottom;
• and
• a refractory metal gate electrode having a lower portion disposed within the hollow, the compound semiconductor body comprising:
• a compound semiconductor structure having a surface;
• a channel layer comprising a compound semiconductor of a first conductivity type, containing a dopant impurity, and having a dopant impurity concentration, the channel layer being located at a region of the surface of the compound semiconductor substrate directly between the gate electrode and the compound semiconductor substrate;
• first active layers comprising the compound semiconductor, of first conductivity type, containing the dopant impurity, and having a dopant impurity concentration, the first active layers being located on regions of the surface of the compound semiconductor substrate in the recess where the channel layer is not present;
• second active layers comprising the compound semiconductor, of the first conductivity type, containing the dopant impurity, and having a dopant impurity concentration, the second active layers being located on regions of the surface of the compound semiconductor substrate sandwiching the recess;
• a first compound semiconductor layer having a second conductivity type, opposite the first conductivity type, containing a dopant impurity, and having a dopant impurity concentration, the first compound semiconductor layer being disposed on a side of the channel layer opposite a side where the refractory metal gate electrode is located;
• and
• second compound semiconductor layers having the second conductivity type, containing a dopant impurity, and having a dopant impurity concentration, the second compound semiconductor layers being disposed on a side of the first active layers opposite a side where the refractory metal gate electrode is located.

A semiconductor device comprising:

• a compound semiconductor body having a surface and a recess at the surface, the recess having a bottom and a hollow in the center of the bottom;
• and
• a refractory metal gate electrode having a lower portion disposed within the hollow, the compound semiconductor body comprising :
• a compound semiconductor structure having a surface;
• a channel layer comprising a compound semiconductor of a first conductivity type, containing a dopant impurity, and having a dopant impurity concentration, the channel layer being located at a region of the surface of the compound semiconductor substrate directly between the gate electrode and the compound semiconductor substrate;
• first active layers comprising the compound semiconductor, of first conductivity type, containing the dopant impurity, and having a dopant impurity concentration, the first active layers being located on regions of the surface of the compound semiconductor substrate in the recess where the channel layer is not present;
• and
• second active layers comprising the compound semiconductor, of the first conductivity type, containing the dopant impurity, and having a dopant impurity concentration, the second active layers being located on regions of the surface of the compound semiconductor substrate sandwiching the recess, wherein each of the first active layers includes a recess at a surface of the respective first active layers opposite the semiconductor substrate and adjacent the hollow, extending from an interface of the channel layer and a refractory metal gate electrode into only part of the respective first active layer.