ABSTRACT
High-density two-dimensional electron gases (2DEGs) used as conducting channels are formed in the preparation of typical AlGaN/GaN heterostructures. GaN HEMTs based on such material are the D-mode HEMTs (D-HEMTs), which require a negative gate bias to be switched off, thus being called the normally on HEMTs. The realization of E-HEMTs fully compatible with D-HEMTs requires special structures or processes, mainly including the thin barrier layer, recessed gate (in combination with the MIS structure), pn junction under the gate, and fluoride ion implantation under the gate.
