Abstract
A method of forming a semiconductor structure includes forming a second III-V compound layer over a first III-V compound layer, wherein a carrier channel is located between the first III-V compound layer and the second III-V compound layer. The method further includes forming a source feature and a drain feature over the second III-V compound layer. The method further includes forming a gate dielectric layer over the second III-V compound layer, wherein the gate dielectric layer is over a top surface of the source feature and over a top surface of the drain feature. The method further includes treating a portion of the gate dielectric layer with fluorine, wherein treating the portion of the gate dielectric layer comprises performing an implantation process using at least one fluorine-containing compound. The method further includes forming a gate electrode over the portion of the gate dielectric layer.