US Patent 7851884 Field-effect transistor, semiconductor chip and semiconductor device

A FET exhibiting excellent uniformity and productivity and having a low noise figure and high associated gain as high-frequency performance, a semiconductor chip having this FET and a semiconductor device having the semiconductor chip. The FET includes a GaAs substrate on which are built up an i-type GaAs layer, an i-type InGaAs two-dimensional electron gas layer and an n-type AlGaAs electron supply layer. A gate electrode is provided on and in linear Schottky contact with the n-type AlGaAs electron supply layer. A n-type InGaP etching stop layer and then an n-type GaAs contact layer at the same lateral position are built up on the n-type AlGaAs electron supply layer, these being spaced away from both sides of the gate electrode. A source electrode and a drain electrode are provided on the n-type GaAs contact layer and are spaced away from edges of the contact layer as electrodes that make band-shaped ohmic contact.