A method of forming a semiconductor structure comprises forming a channel layer; forming a superlattice barrier layer overlying the channel layer, and forming a gate dielectric overlying the superlattice barrier layer. The superlattice barrier layer includes a plurality of alternating first and second layers of barrier material. In addition, the superlattice barrier layer is configured for increasing a transconductance of the semiconductor device by at least a factor of three over a semiconductor device absent such superlattice barrier layer.