Methods of manufacturing high electron mobility transistors having a modified interface region

A method of forming a high electron mobility transistor (HEMT), comprising:

• providing a semiconductor structure comprising a channel layer and a barrier layer sequentially stacked on a substrate;
• forming a first insulating layer on the barrier layer;
• forming a gate contact on the barrier layer, at least a portion of the gate contact within the first insulating layer;
• and
• providing a modified interface region between the first insulating layer and the barrier layer that is laterally separated from a bottom surface of the gate contact.

A method of forming a high electron mobility transistor (HEMT), comprising:

• providing a semiconductor structure comprising a channel layer on a substrate and a barrier layer on the channel layer;
• forming a first insulating layer on the barrier layer and etching an opening in the first insulating layer, the first insulating layer comprising a modified interface region in an interface between the first insulating layer and the barrier layer;
• forming a spacer on the barrier layer in the opening in the first insulating layer;
• and
• forming a gate contact on the barrier layer and the spacer in the opening in the first insulating layer,
• wherein an interface between the spacer and the barrier layer comprises a trap concentration and/or surface potential that is different from a trap concentration and/or surface potential of the modified interface region.