ALUMINUM GALLIUM NITRIDE/GALLIUM NITRIDE HIGH ELECTRON MOBILITY TRANSISTORS HAVING A GATE CONTACT ON A GALLIUM NITRIDE BASED CAP SEGMENT AND METHODS OF FABRICATING SAME

摘要

High electron mobility transistors (HEMTs) and methods of fabricating HEMTsare provided Devices according to embodiments of the present invention includea gallium nitride (GaN) channel layer and an aluminum gallium nitride (AlGaN)barrier layer on the channel layer. A first ohmic contact is provided on thebarrier layer (16) to provide a source electrode (18) and a second ohmiccontact is also provided on the barrier layer (16) and is spaced apart fromthe source electrode (18) to provide a drain electrode (20). A GaN-based capsegment (30) is provided on the barrier layer (16) between the sourceelectrode (18) and the drain electrode (20). The GaN-based cap segment (30)has a first sidewall (31) adjacent and spaced apart from the source electrode(18) and may have a second sidewall (32) adjacent and spaced apart from thedrain electrode (20). A non-ohmic contact is provided on the GaN-based capsegment (30) to provide a gate contact (22). The gate contact (22) has a firstsidewall (27) which is substantially aligned with the first sidewall (31) ofthe GaN-based cap segment (30). The gate contact (22) extends only a portionof a distance between the first sidewall (31) and the second sidewall (32) ofthe GaN-based cap segment (30).