Circuit structure, transistor and semiconductor device

A method comprising:

• epitaxially growing a first semiconductor layer over a substrate;
• epitaxially growing a second semiconductor layer over the first semiconductor layer;
• forming a gate on the second semiconductor layer;
• depositing a passivation film over the gate and the first and second semiconductor layers;
• etching a first opening and a second opening in the passivation film, wherein the etching exposes the second semiconductor layer, and wherein the first opening and the second opening are disposed on opposite sides of the gate;
• depositing ohmic metal layers over the passivation film and in the first and second openings;
• and
• etching a portion of the ohmic metal layers to form a source structure and a drain structure, wherein the source structure comprises:
• a first portion disposed over the first opening;
• and
• a second portion extending over at least a portion of the passivation film between the first portion and the gate, wherein the second portion overlies at least a portion of the gate.

A method comprising:

• epitaxially growing a semiconductor layer over a substrate;
• epitaxially growing a donor-supply layer over the semiconductor layer;
• forming a gate over the donor-supply layer;
• forming a passivation layer over the gate, wherein the passivation layer has a first opening on a first side of the gate and a second opening on a second side of the gate opposite the first side of the gate;
• conformally depositing one or more metal layers over the first opening, the second opening, and the passivation layer;
• and
• etching the one or more metal layers to form a third opening in the one or more metal layers, wherein the third opening exposes the passivation layer and is disposed between the gate and the second opening of the passivation layer,
• wherein after the etching the one or more metal layers contiguously extend from the first opening to a first distance on the second side of the gate.