Nitride based transistors on semi-insulating silicon carbide substrates
OwnerScott Thomas Sheppard, Scott Thomas Allen +1inventors
InventorsScott Thomas Sheppard, Scott Thomas Allen, John Williams Palmour
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Abstract
A high electron mobility transistor (HEMT) is disclosed that includes a semi-insulating silicon carbide substrate, an aluminum nitride buffer layer on the substrate, an insulating gallium nitride layer on the buffer layer, an active structure of aluminum gallium nitride on the gallium nitride layer, a passivation layer on the aluminum gallium nitride active structure, and respective source, drain and gate contacts to the aluminum gallium nitride active structure.
Claims21
A high electron mobility transistor for generating high power signals within the RF spectrum, comprising:
- a semi-insulating substrate;
- a transition layer on said substrate;
- a Group III nitride heterojunction on said transition layer, said heterojunction comprising:
- an undoped gallium nitride insulating layer on said transition layer, and
- an active region on said insulating layer, said active region comprising:
- a first undoped AlGaN layer on said insulating layer;
- a conductively doped AlGaN layer on said first undoped AlGaN layer, and
- a second undoped AlGaN layer on said doped AlGaN layer;
- an undoped layer on said active region;
- and
- respective source, gate, and drain contacts electrically connected to said heterojunction,
- wherein a two dimensional electron gas develops in said insulating layer directly beneath said first undoped AlGaN layer of said active region, said two dimensional electron gas providing a conductive path from said source contact to said drain contact.
A high electron mobility transistor for generating high power signals within the RF spectrum, comprising:
- a substrate that is sufficiently non-conductive to reduce parasitic charge in the substrate;
- a transition layer on said substrate;
- a Group III nitride heterojunction on said transition layer, said heterojunction comprising:
- an undoped gallium nitride insulating layer on said transition layer, and
- an active region on said insulating layer, said active region comprising:
- a first undoped AlGaN layer on said insulating layer,
- a conductively doped AlGaN layer on said first undoped AlGaN layer, and
- a second undoped AlGaN layer on said doped AlGaN layer;
- respective source, gate, and drain contacts electrically connected to said heterojunction,
- wherein a two dimensional electron gas develops in said insulating layer directly beneath said first undoped AlGaN layer of said active region, said two dimensional electron gas providing a conductive path from said source contact to said drain contact.
A high electron mobility transistor (HEMT) that is formed on a substrate with a reduced capacitance for charge and that has a transitional layer at the top of the substrate accommodating the growth of Group III nitride layers thereon, the high electron mobility transistor comprising:
- adjacent layers of aluminum gallium nitride and gallium nitride,
- wherein said gallium nitride layer is undoped, and
- said aluminum gallium nitride layer is formed of a first undoped layer of AlGaN on said GaN layer;
- a donor doped layer of AlGaN on said first undoped AlGaN layer, and a second undoped AlGaN layer on said donor doped AlGaN layer;
- and
- contacts electrically connected to said heterojunction to define respective source, gate, and drain portions of a transistor;
- wherein a two dimensional electron gas develops in said insulating layer directly beneath said first undoped AlGaN layer of said active region, said two dimensional electron gas providing a conductive path from said source contact to said drain contact.
A high electron mobility transistor for generating high power signals within the RF spectrum, comprising:
- a semi-insulating substrate;
- a transition layer on said substrate;
- a Group III nitride heterostructure on said transition layer, said heterostructure comprising:
- an undoped gallium nitride insulating layer on said transition layer;
- an active region on said insulating layer, said active region comprising:
- a first undoped AlGaN layer on said insulating layer;
- a conductively doped AlGaN layer on said first undoped AlGaN layer;
- a second undoped AlGaN layer on said doped AlGaN layer;
- respective source, gate, and drain contacts electrically connected to said heterostructure,
- wherein said transition layer comprises a sufficient concentration of aluminum nitride to provide a crystal structure transition between said semi-insulating substrate and said heterostructure, and
- wherein a two dimensional electron gas develops in said insulating layer directly beneath said first undoped AlGaN layer of said active region, said two dimensional electron gas providing a conductive path from said source contact to said drain contact.
A high electron mobility transistor for generating high power signals within the RF spectrum, comprising:
- a substrate that is sufficiently non-conductive to reduce parasitic charge in the substrate;
- a transition layer on said substrate;
- a Group III nitride heterostructure on said transition layer, said heterostructure comprising:
- an undoped gallium nitride insulating layer on said transition layer, and
- an active region on said insulating layer, said active region comprising:
- a first undoped AlGaN layer on said insulating layer;
- a conductively doped AlGaN layer on said first undoped AlGaN layer;
- a second undoped AlGaN layer on said doped AlGaN layer;
- respective source, gate, and drain contacts electrically connected to said heterostructure,
- wherein said transition layer comprises a sufficient concentration of aluminum nitride to provide a crystal structure transition between said substrate and said heterostructure, and
- wherein a two dimensional electron gas develops in said insulating layer directly beneath said first undoped AlGaN layer of said active region, said two dimensional electron gas providing a conductive path from said source contact to said drain contact.
Dependencies are inferred from the claim text.