Iii-n transistors with features for improved performance

An integrated circuit (IC) structure, comprising:

• a transistor, comprising:
• a source region and a drain region comprising a doped semiconductor material,
• a channel region comprising a III-N material, wherein the channel region is between the source region and the drain region, and
• a gate electrode over at least a portion of the channel region;
• a first layer over the channel region, the first layer comprising oxygen;
• a second layer over the first layer, the second layer comprising nitrogen;
• a third layer over the second layer, the third layer comprising oxygen;
• and
• a fourth layer over the third layer, the fourth layer comprising nitrogen.

An integrated circuit (IC) structure, comprising:

• a transistor, comprising:
• a source region and a drain region comprising a doped semiconductor material,
• a channel region comprising a III-N material, wherein the channel region is between the source region and the drain region, and
• a gate electrode over at least a portion of the channel region;
• and
• an isolation trench adjacent to one of the source region or the drain region, wherein the isolation trench includes a liner of a material comprising nitrogen and a fill of an insulator material comprising oxygen.