Abstract
A method of forming a high electron mobility transistor (HEMT) includes forming a second III-V compound layer on a first III-V compound layer, forming a source feature and a drain feature on the second III-v compound layer, depositing a p-type layer on a portion of the second III-V compound layer between the source feature and the drain feature, and forming a gate electrode on the p-type layer. A carrier channel is located between the first III-V compound layer and the second III-V compound layer.