US 5,686,740 A · Field effect transistor with recessed gate

Abstract

In an FET structure, an n-type AlGaAs electron supplying layer is provided above a GaAs channel layer, and a low-resistivity n-type GaAs contact layer (the first semiconductor layer) is provided between the source/drain electrode and the electron supplying layer. A high-resistivity AlGaAs layer (the second semiconductor layer) is formed on the sidewalls of the contact layer and the immediately adjacent region between the gate electrode and the contact layer. According to the present invention, since a semiconductor film is used as the thin film formed on the sidewall and the adjacent electron supplying layer instead of a conventional insulating film, and moreover since AlGaAs is substantially lattice matched to GaAs and has a larger band width, parasitic resistance is reduced significantly, and the fluctuation of device performance properties is prevented while still maintaining high breakdown voltage. A semiconductor layer having a conduction type opposite that of the contact layer may also be used in place of the high resistivity AlGaAs layer.

Claims21

Dependent claims

A field effect transistor comprising:

a channel layer to conduct carriers;
a source electrode, a drain electrode, and a gate electrode formed or said channel layer;
a first semiconductor layer interposed between said source electrode and said channel layer, and between said drain electrode and said channel layer, said first semiconductor layer having an opening in which said gate electrode is formed, said opening being defined by oppositely facing sidewalls of said first semiconductor layer;
a second semiconductor layer having an electrical conductivity different from the electrical conductivity of the first semiconductor layer, said second semiconductor layer being formed on at least one of said sidewalls of the first semiconductor layer and on at least a part of said channel layer between said gate electrode and said sidewall;
wherein a conduction type of said second semiconductor layer is opposite to a conduction type of said first semiconductor layer.

2 more elements

Dependencies are inferred from the claim text.

Field effect transistor with recessed gate

Life of this patent

Field effect transistor with recessed gate

Life of this patent

Abstract

Claims21