Methods of fabricating nitride-based transistors having regrown ohmic contact regions

A method of fabricating a transistor, comprising:

• forming a nitride-based channel layer on a substrate;
• forming a barrier layer on the nitride-based channel layer;
• forming a contact recess in the barrier layer to expose a contact region of the nitride-based channel layer;
• forming a contact layer on the exposed contact region of the nitride-based channel layer using a low temperature deposition process;
• forming an ohmic contact on the contact layer;
• forming a gate contact disposed on the barrier layer adjacent the ohmic contact;
• forming a first dielectric layer on the barrier layer;
• wherein forming a gate contact comprises forming a gate contact in the first dielectric layer;
• and
• wherein forming a contact recess comprises forming an ohmic contact recess in the first dielectric layer and the barrier layer that expose a portion of the nitride-based channel layer.

A method of fabricating a transistor, comprising:

• forming a nitride-based channel layer on a substrate;
• forming a barrier layer on the nitride-based channel layer;
• forming a contact recess in the baffler layer to expose a contact region of the nitride-based channel layer;
• forming a contact layer on the exposed contact region of the nitride-based channel layer using a low temperature deposition process;
• forming an ohmic contact on the contact layer;
• forming a gate contact disposed on the baffler layer adjacent the ohmic contact;
• forming holes in the channel layer adjacent the contact regions;
• placing n-type nitride-based semiconductor material in the holes;
• and
• wherein forming an ohmic contact on the contact layer comprises forming an ohmic contact on the contact layer and on the n-type nitride-based semiconductor material in the holes.

A method of fabricating a transistor, comprising:

• forming a nitride-based channel layer on a substrate;
• forming a barrier layer on the nitride-based channel layer;
• forming a masking layer on the barrier layer;
• patterning the masking layer and the barrier layer to provide a contact opening that exposes a portion of the nitride-based channel layer;
• forming a contact layer on the exposed portion of the nitride-based channel layer and the masking layer;
• selectively removing the masking layer and a portion of the contact layer on the masking layer to provide a nitride-based contact region;
• forming an ohmic contact on the nitride-based contact region;
• and
• forming a gate contact disposed on the barrier layer adjacent the ohmic contact.