A transistor device includes a semiconductor epitaxial layer structure including a channel layer and a barrier layer on the channel layer, wherein the barrier layer has a higher bandgap than the channel layer. A modified access region is provided at an upper surface of the barrier layer opposite the channel layer. The modified access region includes a material having a lower surface barrier height than the barrier layer. A source contact and a drain contact are formed on the barrier layer, and a gate contact is formed between source contact and the drain contact.

A transistor device according to some embodiments includes a channel layer, a barrier layer on the channel layer, and source and drain contacts on the barrier layer, and a gate contact on the barrier layer between the source and drain contacts. The channel layer includes a sub-layer having an increased doping concentration level relative to a remaining portion of the channel layer. The presence of the sub-layer may reduce drain lag without substantially increasing gate lag.

A semiconductor structure includes a substrate. The semiconductor structure further includes a buffer layer over the substrate, wherein the buffer layer comprises a plurality of III-V layers, and a dopant type of each III-V layer of the plurality of III-V layers is opposite to a dopant of adjacent III-V layers of the plurality of III-V layers. The semiconductor structure further includes an active layer over the buffer layer. The semiconductor structure further includes a dielectric layer over the active layer.

A gallium nitride based monolithic microwave integrated circuit includes a substrate, a channel layer on the substrate and a barrier layer on the channel layer. A recess is provided in a top surface of the barrier layer. First gate, source and drain electrodes are provided on the barrier layer opposite the channel layer, with a bottom surface of the first gate electrode in direct contact with the barrier layer. Second gate, source and drain electrodes are also provided on the barrier layer opposite the channel layer. A gate insulating layer is provided in the recess in the barrier layer, and the second gate electrode is on the gate insulating layer opposite the barrier layer and extending into the recess. The first gate, source and drain electrodes comprise the electrodes of a depletion mode transistor, and the second gate, source and drain electrodes comprise the electrodes of an enhancement mode transistor.

A semiconductor device includes a channel layer, a barrier layer, source contact and a drain contact, a doped group III-V layer, and a gate electrode. The barrier layer is positioned above the channel layer. The source contact and the drain contact are positioned above the barrier layer. The doped group III-V layer is positioned above the barrier layer and between the first drain contact and the first source contact. The first doped group III-V layer has a first non-vertical sidewall and a second non-vertical sidewall. The gate electrode is positioned above the doped group III-V layer and has a third non-vertical sidewall and a fourth non-vertical sidewall. A horizontal distance from the first non-vertical sidewall to the third non-vertical sidewall is different than a horizontal distance from the second non-vertical sidewall to the fourth non-vertical sidewall.

An epitaxial wafer according to the present disclosure includes: a substrate; a buffer layer formed of a crystal having the composition formula represented by Al.sub.xGa.sub.yIn.sub.zN (x+y+z=1, y>0) on the substrate; a back-barrier layer formed of a crystal having the composition formula represented by Al.sub.xGa.sub.yIn.sub.zN (x+y+z=1, y>0, z>0) on the buffer layer; a channel layer formed of a crystal having the composition formula represented by Al.sub.xGa.sub.yIn.sub.zN (x+y+z=1, y>0) on the back-barrier layer; and an electron-supply layer formed of a crystal having the composition formula represented by Al.sub.xGa.sub.yIn.sub.zN (x+y+z=1, x>0) on the channel layer. The channel layer is constituted with an upper channel layer underneath the electron-supply layer and a lower channel layer on the back-barrier layer, and the lower channel layer has a C concentration higher than the upper channel layer and contains Si.

A semiconductor device includes a substrate, a semiconductor stacking portion formed on the substrate, a silicon nitride passivation film covering the surface of the semiconductor stacking portion, and oxygen atoms existing at an interface between the silicon nitride passivation film and the semiconductor stacking portion. The semiconductor stacking portion includes a plurality of nitride semiconductor layers. The interfacial oxygen content at the passivation film and stacking portion interface is 0.6×10.sup.15 oxygen atoms/cm.sup.2 or less.

Disclosed herein are IC structures, packages, and devices that include planar III-N transistors with wrap-around gates and/or one or more wrap-around source/drain (S/D) contacts. An example IC structure includes a support structure (e.g., a substrate) and a planar III-N transistor. The transistor includes a channel stack of a III-N semiconductor material and a polarization material, provided over the support structure, a pair of S/D regions provided in the channel stack, and a gate stack of a gate dielectric material and a gate electrode material provided over a portion of the channel stack between the S/D regions, where the gate stack at least partially wraps around an upper portion of the channel stack.

An apparatus for reducing lag includes a substrate; a group III-Nitride barrier layer; a source electrically coupled to the group III-Nitride barrier layer; a gate on the group III-Nitride barrier layer; a drain electrically coupled to the group III-Nitride barrier layer; a p-region being arranged at or below the group III-Nitride barrier layer; and a gate control circuit configured to control a gate voltage of the gate. Additionally, at least a portion of the p-region is arranged vertically below at least one of the following: the source, the gate, and an area between the gate and the drain.

An apparatus includes a substrate; a group III-Nitride barrier layer; a source electrically coupled to the group III-Nitride barrier layer; a gate on the group III-Nitride barrier layer; a drain electrically coupled to the group III-Nitride barrier layer; a p-region being arranged at or below the group III-Nitride barrier layer; and a recovery enhancement circuit configured to reduce an impact of an overload received by the gate. Additionally, at least a portion of the p-region is arranged vertically below at least one of the following: the source, the gate, an area between the gate and the drain.