An embodiment high electron mobility transistor (HEMT) includes a gate electrode over a semiconductor substrate and a multi-layer semiconductor cap over the semiconductor substrate and adjacent the gate electrode. The multi-layer semiconductor cap includes a first semiconductor layer and a second semiconductor layer comprising a different material than the first semiconductor layer. The first semiconductor layer is laterally spaced apart from the gate electrode by a first spacing, and the second semiconductor layer is spaced apart from the gate electrode by a second spacing greater than the first spacing.

A semiconductor device includes: a substrate; a nitride semiconductor film on the substrate; a schottky electrode on the nitride semiconductor film; a first insulating film on the nitride semiconductor film, contacting at least part of a side surface of the schottky electrode, forming an interface with the nitride semiconductor film and formed of SiN; and a second insulating film covering the schottky electrode and the first insulating film and formed of AlO whose atomic layers are alternately disposed.

An embodiment high electron mobility transistor (HEMT) includes a gate electrode over a semiconductor substrate and a multi-layer semiconductor cap over the semiconductor substrate and adjacent the gate electrode. The multi-layer semiconductor cap includes a first semiconductor layer and a second semiconductor layer comprising a different material than the first semiconductor layer. The first semiconductor layer is laterally spaced apart from the gate electrode by a first spacing, and the second semiconductor layer is spaced apart from the gate electrode by a second spacing greater than the first spacing.

An embodiment high electron mobility transistor (HEMT) includes a gate electrode over a semiconductor substrate and a multi-layer semiconductor cap over the semiconductor substrate and adjacent the gate electrode. The multi-layer semiconductor cap includes a first semiconductor layer and a second semiconductor layer comprising a different material than the first semiconductor layer. The first semiconductor layer is laterally spaced apart from the gate electrode by a first spacing, and the second semiconductor layer is spaced apart from the gate electrode by a second spacing greater than the first spacing.

A method of manufacturing a semiconductor device includes: forming an electron transit layer; forming an electron supply layer; forming a protective film; forming a zinc oxide film; forming a sacrifice layer; forming a first opening and a second opening in the sacrifice layer and the zinc oxide film; forming a third opening connecting to the first opening and a fourth opening connecting to the second opening; forming, by acid treatment using a weakly acidic solution, a first gap in a first portion exposed to the first opening of the zinc oxide film, and a second gap in a second portion exposed to the second opening of the zinc oxide film; forming, after the acid treatment, a source region on a bottom surface of the third opening and a drain region on a bottom surface of the fourth opening; and removing the zinc oxide film.

A method for fabricating high electron mobility transistor (HEMT) includes the steps of forming a buffer layer on a substrate, forming a barrier layer on the buffer layer, forming a p-type semiconductor layer on the barrier layer, forming a titanium nitride (TiN) layer on the p-type semiconductor layer as a nitrogen to titanium (N/Ti) ratio of the TiN layer is greater than 1, forming a passivation layer on the TiN layer and the barrier layer, removing the passivation layer to form an opening, forming a gate electrode in the opening, and then forming a source electrode and a drain electrode adjacent to two sides of the gate electrode on the barrier layer.

The present disclosure provides a GaN-based semiconductor structure, including: a substrate; a channel layer; a barrier layer, where the channel layer and the barrier layer each include a channel region, a source region and a drain region; one or more grooves provided in at least one of the source region or the drain region, where, for each of the grooves, a length of a first side edge adjacent to the channel region and located on a bottom wall of the groove is larger than a length of an orthographic projection of the first side edge on a vertical plane in a length direction of the channel region; a source region N-type ion heavily-doped layer and a drain region N-type ion heavily-doped layer; and a gate electrode, a source electrode, and a drain electrode.

According to one embodiment, a semiconductor device includes first to third electrodes, first and second semiconductor regions, and a first member. The first semiconductor region includes Al.sub.x1Ga.sub.1-x1N (0x1<1). The second semiconductor region includes Al.sub.x2Ga.sub.1-x2N (x1<x21). The first member includes first and second regions. The second region is between the first region and the first electrode region of the second electrode. A part of the second region is between the second semiconductor portion of the second semiconductor region and the second electrode region. The second region includes at least one first element selected from the group consisting of Ti, Al, Ga, Ni, Nb, Mo, Ta, Hf, V, and Au. The first region does not include the first element, or a concentration of the first element in the first region is lower than a concentration of the first element in the second region.

A nitride semiconductor device includes a first nitride semiconductor layer including a channel layer and a barrier layer, a second nitride semiconductor layer, and a third nitride semiconductor layer. The channel layer and the barrier layer are interposed between the second nitride semiconductor layer and the third nitride semiconductor layer. In a cross-sectional view including a first axis and a second axis, the second nitride semiconductor layer includes a first covering portion covering a portion of a third surface of an insulating layer, and the third nitride semiconductor layer includes a second covering portion covering a portion of the third surface.

A disclosed structure includes an enhancement mode high electron mobility transistor (HEMT). The HEMT includes a barrier layer with a thick portion positioned laterally between thin portions and a gate. The gate includes a semiconductor layer (e.g., a P-type III-V semiconductor layer) on the thick portion of the barrier layer and having a thick portion positioned laterally between thin portions. The gate also includes a gate conductor layer on and narrower than the thick portion of the semiconductor layer, so end walls of the gate are stepped. Thin portions of the barrier layer near these end walls minimize or eliminate charge build up in a channel layer below. To block current paths around the gate, isolation regions can be below the thin portions of the barrier layer offset from the semiconductor layer. The structure can further include alternating e-mode and d-mode HEMTs. Also disclosed are associated method embodiments.