Field Effect Transistor and Device Thereof

A field effect transistor comprising:

• a carrier transit layer in a stacked layer structure provided with a plurality of nitride semiconductor layers;
• a gate electrode provided on the stacked layer structure;
• and
• a source electrode and a drain electrode placing the gate electrode in between;
• wherein the stacked layer structure has a step portion having a side surface exposing an end portion of the carrier transit layer at each side of the gate electrode, the source electrode and drain electrode, which are at least connected to the end portion of the carrier transit layer, are provided respectively on the side surface of the step portion, a part of the source electrode and drain electrode are provided respectively on a surface of an upper step of the step portion, a part of source electrode and drain electrode provided on the upper step of the step portion have, in carrier transit direction, a distance L of L≦10 μm from the side surface to each end portion of the electrodes at the gate electrode side, and in a range of the distance L [μm] from 1 to 10, a contact resistance Rc [Ωmm] of the source and drain electrodes at the distance L determined by TLM method is smaller than a line segment represented by (L, Rc)=(1, 2) and (10, 5).

A field effect transistor comprising:

• a carrier transit layer in a stacked layer structure provided with a plurality of nitride semiconductor layers;
• a gate electrode provided on the stacked layer structure;
• and
• a source electrode and drain electrode placing the gate electrode in between;
• wherein the stacked layer structure has a step portion having a side surface exposing an end portion of the carrier transit layer at each side of the gate electrode, the source electrode and drain electrode, which are at least connected to the end portion of the carrier transit layer, are provided respectively on the side surface of the step portion, a part of the source electrode and drain electrode are provided respectively on a surface of an upper step of the step portion, and a contact resistance of an upper step portion of the source electrode and drain electrode is higher than a contact resistance of end portion of the carrier transit layer at the side surface or adjacent area thereof.

A field effect transistor comprising:

• a carrier transit layer in a stacked layer structure provided with a plurality of nitride semiconductor layers;
• a gate electrode provided on the stacked layer structure;
• and
• a source electrode and drain electrode placing the gate electrode in between;
• wherein the stacked layer structure has a step portion having a side surface exposing an end portion of the carrier transit layer at each side of the gate electrode, the source electrode and drain electrode, which are at least connected to the end portion of the carrier transit layer, are provided respectively on the side surface of the step portion, a part of the source electrode and drain electrode are provided respectively on a surface of an upper step of the step portion, and a part of each source electrode and drain electrode provided on the upper step of the step portion have, in carrier transit direction, a distance L of 0.1≦L≦5 μm from the side surface to end portion of the respective electrodes at the gate electrode side.