In an embodiment, a substrate structure includes a support substrate, a buffer structure arranged on the support substrate, the buffer structure including an intentionally doped superlattice laminate, an unintentionally doped first Group III nitride layer arranged on the buffer structure, a second Group III nitride layer arranged on the first Group III nitride layer forming a heterojunction therebetween, and a blocking layer arranged between the heterojunction and the buffer structure. The blocking layer is configured to block charges from entering the buffer structure.

A compound semiconductor device includes a compound semiconductor layer, a gate electrode disposed above the compound semiconductor layer, and source and drain electrodes disposed above the compound semiconductor layer with the gate electrode between the source and drain electrodes, wherein the compound semiconductor layer has a groove in a surface thereof at least between the source electrode and the gate electrode in a region between the source electrode and the drain electrode, the groove gradually deepened toward the source electrode.

Strain is used to enhance the properties of p- and n-materials so as to improve the performance of III-N electronic and optoelectronic devices. In one example, transistor devices include a channel aligned along uniaxially strained or relaxed directions of the III-nitride material in the channel. Strain is introduced using buffer layers or source and drain regions of different composition.

A method for forming a III-V construction over a group IV substrate comprises providing an assembly comprising the group IV substrate and a dielectric thereon. The dielectric layer comprises a trench exposing the group IV substrate. The method further comprises initiating growth of a first III-V structure in the trench, continuing growth out of the trench on top of the bottom part, growing epitaxially a sacrificial second III-V structure on the top part of the first III-V structure, and growing epitaxially a third III-V structure on the sacrificial second III-V structure. The third III-V structure comprises a top III-V layer. The method further comprises physically disconnecting a first part of the top layer from a second part thereof, and contacting the sacrificial second III-V structure with the liquid etching medium.

A method of manufacturing a semiconductor device is provided. The method includes forming a channel layer and an active layer over a substrate; forming a doped epitaxial layer over the active layer; patterning the doped epitaxial layer, the active layer, and the channel layer to form a fin structure comprising a doped epitaxial fin portion, an active fin portion below the doped epitaxial fin portion, and a channel fin portion below the active fin portion; removing the doped epitaxial fin portion; and forming a gate electrode at least partially extending along a sidewall of the fin structure to form a Schottky barrier between the gate electrode and the fin structure after removing the doped epitaxial fin portion.

A high electron mobility transistor (HEMT) device comprising a substrate, a plurality of semiconductor layers provided on the substrate, and a source terminal, a drain terminal and at least one gate terminal provided on the plurality of semiconductor layers. The HEMT also includes a metal ring formed on the plurality of semiconductor layers around the source terminal, the drain terminal and the at least one gate terminal, where the metal ring operates to shift the pinch-off voltage of the device. In one embodiment, the metal ring includes an ohmic portion and an electrode portion, where both the ohmic portion and the electrode portion include a lower titanium layer, a middle platinum layer and an upper gold layer.

Some embodiments of this disclosure provide a semiconductor device. The semiconductor device includes: a substrate; a barrier layer, disposed on the substrate; a first channel layer, disposed on the barrier layer; a first gate conductor, disposed on the first channel layer; and a first doped semiconductor layer, disposed between the first gate conductor and the first channel layer, where a forbidden band width of the barrier layer is greater than a forbidden band width of the first channel layer.

Some embodiments of this disclosure provide a semiconductor device. The semiconductor device includes: a substrate; a barrier layer, disposed on the substrate; a first channel layer, disposed on the barrier layer; a first gate conductor, disposed on the first channel layer; and a first doped semiconductor layer, disposed between the first gate conductor and the first channel layer, where a forbidden band width of the barrier layer is greater than a forbidden band width of the first channel layer.

A method of manufacturing a semiconductor device is provided. The method includes forming a channel layer and an active layer over a substrate; forming a doped epitaxial layer over the active layer; patterning the doped epitaxial layer, the active layer, and the channel layer to form a fin structure comprising a doped epitaxial fin portion, an active fin portion below the doped epitaxial fin portion, and a channel fin portion below the active fin portion; removing the doped epitaxial fin portion; and forming a gate electrode at least partially extending along a sidewall of the fin structure to form a Schottky barrier between the gate electrode and the fin structure after removing the doped epitaxial fin portion.

A semiconductor device includes a substrate, a channel layer, an active layer, and a gate electrode. The channel layer has a fin portion over the substrate. The active layer is over at least the fin portion of the channel layer. The active layer is configured to cause a two-dimensional electron gas (2DEG) to be formed in the channel layer along an interface between the channel layer and the active layer. The gate electrode is in contact with a sidewall of the fin portion of the channel layer.