Patent ID: 11929402
Assignee: NOVEL CRYSTAL TECHNOLOGY, INC.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A field-effect transistor for normally-off operation, comprising:
a Ga2O3-based semiconductor layer that is formed of a β-type Ga2O3-based single crystal;
a source region and a drain region that are formed inside the Ga2O3-based semiconductor layer and are n-type regions doped with an n-type impurity;
a channel region which is continuous between the source region and the drain region and located inside the Ga2O3-based semiconductor layer, the channel region that is an n-region doped with an n-type impurity and has n-type conductivity weaker than the source and the drain regions;
an undoped region located inside the Ga2O3-based semiconductor layer and below the source, the drain and the channel regions, the undoped region that does not contain any intentionally doped impurity and has insulating properties or has an n-type conductivity weaker than the channel region;
a gate insulating film that is formed directly on a surface of the Ga2O3-based semiconductor layer so as to be in contact with the channel region;
a gate electrode that is formed, via the gate insulating film, on the channel region;
a source electrode connected to the source region; and
a drain electrode connected to the drain region,
wherein an interface charge comprising a negative charge is formed on a surface or in an upper portion of the channel region, and
wherein a gate threshold voltage is not less than 4.5V and not more than power supply voltage.