Fujitsu Corporation

Shigeru Kuroda

Yoshimi Yamashita

Sumio Yamamoto

Kinjiro Kosemura

Hidetoshi Ishiwari

Masashi Shima

Takashi Mimura

Naoki Hara

Seishi Notomi

A field effect transistor includes a substrate of a compound semiconductor material, source and drain regions formed in the substrate, a channel region defined between the source and said drain regions, a gate electrode provided on the substrate so as to cover the channel region, and a pair of diffusion suppressing regions provided in the substrate respectively at both lateral ends of the channel region, each of the diffusion suppressing regions containing an electrically inert element that suppresses a diffusion of a dopant element therethrough.

Compound semiconductor field effect transistor having a controlled

An ohmic contact layer is provided between an n-GaAs/n-AlGaAs/undoped GaAs double-heterojunction structure and source/drain electrodes in a high electron mobility transistor. The ohmic contact layer comprises In.sub.x Ga.sub.1-x As or Ge. The ohmic contact layer has a function of considerably reducing a specific contact resistance of a barrier formed at an interface between the ohmic contact layer and the source and drain electrodes. Thereby, a nonalloyed ohmic contact is formed between the source and drain electrodes and source and drain regions formed in the undoped GaAs layer.

Compound semiconductor device having nonalloyed ohmic contacts

Disclosed is a method of producing a compound semiconductor device comprising an enhancement-mode transistor and a depletion-mode transistor, each of which has a heterojunction and utilizes a two-dimensional electron gas. The method of producing the device comprises the steps of: forming an undoped GaAs channel layer on a semi-insulating GaAs substrate; forming an N-type AlGaAs electron-supply layer so as to form the heterojunction; forming an N-type GaAs layer; forming an AlGaAs layer; selectively etching the AlGaAs layer to form a recess; performing an etching treatment using an etchant which can etch rapidly GaAs and etch slowly AlGaAs to form simultaneously grooves for gate electrodes of the enhancement-mode transistor and the depletion-mode transistor, the bottoms of the grooves being in the N-type AlGaAs layer and the distance between the bottoms being equal to the thickness of the AlGaAs layer; and forming simultaneously the gate electrodes in the grooves.

Method of producing a two-dimensional electron gas semiconductor device

A compound semiconductor device comprises an enhancement-mode transistor and a depletion-mode transistor, each of which has a heterojunction and utilizes a two-dimensional electron gas. The method of producing the device comprises the steps of: forming an undoped GaAs channel layer on a semi-insulating GaAs substrate; forming an N-type AlGaAs electron-supply layer so as to form the heterojunction; forming an N-type GaAs layer; forming an AlGaAs layer; selectively etching the AlGaAs layer to form a recess; performing an etching treatment using an etchant which can etch rapidly GaAs and etch slowly AlGaAs to form simultaneously grooves for gate electrodes of the enhancement-mode transistor and the depletion-mode transistor, the bottoms of the grooves being in the N-type AlGaAs layer and the distance between the bottoms being equal to the thickness of the AlGaAs layer; and forming simultaneously the gate electrodes in the grooves.

HEMT with etch-stop

A method of manufacturing a GaAS semiconductor device of an E/D construction having a GaAs/AlGaAs heterojunction and utilizing a two-dimensional electron gas, which includes the steps of forming a heterojunction semiconductor substrate and etching a portion of the substrate to provide a gate portion of a depletion-mode FET. When the substrate of a semi-insulating GaAs layer, an undoped GaAs, an N-type AlGaAs layer providing an electron-supply layer, and a GaAs layer is formed, the GaAs layer is composed of a first GaAs layer, an etching stoppable AlGaAs layer, and a second GaAs layer, the first GaAs layer being formed on the N-type GaAs layer. The etching for provision of the gate portion is carried out by a dry etching method using an etchant of CCl.sub.2 F.sub.2 gas, so that the second GaAs layer can be etched but the AlGaAs layer cannot be etched. Thus, the thickness of the layers between a gate electrode of the depletion-mode FET and the GaAs/AlGaAs heterojunction plane is determined by the formation of the heterojunction substrate, and consequently a better uniformity of the threshold voltage of depletion-mode FET's is obtained.

GaAs semiconductor device

A method of manufacturing a GaAs semiconductor device of an E/D construction having a GaAs/AlGaAs heterojunction and utilizing two-dimensional electron gas, which includes the steps of forming a heterojunction semiconductor substrate and etching a portion of the substrate to provide a gate portion of a depletion-mode FET. When the substrate of a semi-insulating GaAs layer, an undoped GaAs, an N-type AlGaAs layer providing an electron-supply layer, and a GaAs layer is formed, the GaAs layer is composed of a first GaAs layer, an etching stoppable AlGaAs layer, and a second GaAs layer, the first GaAs layer being formed on the N-type GaAs layer. The etching for provision of the gate portion is carried out by a dry etching method using an etchant of CCl.sub.2 F.sub.2 gas, so that the second GaAs layer can be etched but the AlGaAs layer cannot be etched. Thus, the thickness of the layers between a gate electrode of the depletion-mode FET and the GaAs/AlGaAs heterojunction plane is determined by the formation of the heterojunction substrate, and consequently a better uniformity of the threshold voltage of depletion-mode FETs is obtained.

Growing community of inventors

Hadano, Japan

Shigeru Kuroda