Abstract: A semiconductor die includes a silicon carbide (SiC) substrate and a metal stack. The SiC substrate has a first surface including a semiconductor layer thereon and a second surface that is opposite the first surface. The metal stack has an upper surface that attaches to the second surface of the SiC substrate and a lower surface that is opposite the upper surface. The metal stack includes a eutectic solder layer and a noble metal layer on the eutectic solder layer. The noble metal layer comprises a final metal layer on the lower surface.

Abstract: A transistor device includes a first unit subcell including having a first active region width extending in a first direction, and a second unit subcell having a second active region width extending in the first direction and arranged adjacent the first unit subcell in the first direction. The first unit subcell and the second unit subcell share a common drain contact and have separate gate contacts that are aligned in the first direction. Each unit subcell includes a field plate that is connected to a source contact outside the active region and that does not cross over the gate contact.

Abstract: Transistors are fabricated by forming a nitride-based semiconductor barrier layer on a nitride-based semiconductor channel layer and forming a protective layer on a gate region of the nitride-based semiconductor barrier layer. Patterned ohmic contact metal regions are formed on the barrier layer and annealed to provide first and second ohmic contacts. The annealing is carried out with the protective layer on the gate region. A gate contact is also formed on the gate region of the barrier layer. Transistors having protective layer in the gate region are also provided as are transistors having a barrier layer with a sheet resistance substantially the same as an as-grown sheet resistance of the barrier layer.

Abstract: Methods of fabricating a semiconductor device include forming a first semiconductor layer of a first conductivity type and having a first dopant concentration, and forming a second semiconductor layer on the first semiconductor layer. The second semiconductor layer has a second dopant concentration that is less than the first dopant concentration. Ions are implanted into the second semiconductor layer to form an implanted region of the first conductivity type extending through the second semiconductor layer to contact the first semiconductor layer. A first electrode is formed on the implanted region of the second semiconductor layer, and a second electrode is formed on a non-implanted region of the second semiconductor layer. Related devices are also discussed.

Abstract: Methods of forming a semiconductor device include forming a dielectric layer on a Group III-nitride semiconductor layer, selectively removing portions of the dielectric layer over spaced apart source and drain regions of the semiconductor layer, implanting ions having a first conductivity type directly into the source and drain regions of the semiconductor layer, annealing the semiconductor layer and the dielectric layer to activate the implanted ions, and forming metal contacts on the source and drain regions of the semiconductor layer.

Abstract: A semiconductor structure includes a Group III-nitride semiconductor layer, a protective layer on the semiconductor layer, a distribution of implanted dopants within the semiconductor layer, and an ohmic contact extending through the protective layer to the semiconductor layer.

Abstract: Semiconductor device structures and methods of fabricating semiconductor devices structures are provided that include a semi-insulating or insulating GaN epitaxial layer on a conductive semiconductor substrate and/or a conductive layer. The semi-insulating or insulating GaN epitaxial layer has a thickness of at least about 4 ?m. GaN semiconductor device structures and methods of fabricating GaN semiconductor device structures are also provided that include an electrically conductive SiC substrate and an insulating or semi-insulating GaN epitaxial layer on the conductive SiC substrate. The GaN epitaxial layer has a thickness of at least about 4 ?m.

Abstract: A III-Nitride field-effect transistor, specifically a HEMT, comprises a channel layer, a barrier layer on the channel layer, an etch stop layer on the cap layer, a dielectric layer on the etch stop layer, a gate recess that extends to the barrier layer, and a gate contact in the gate recess. The etch stop layer may reduce damage associated with forming the recessed gate by not exposing the barrier layer to dry etching. The etch stop layer in the recess is removed and the remaining etch stop layer serves as a passivation layer.

Abstract: Methods of fabricating a semiconductor device include forming a first semiconductor layer of a first conductivity type and having a first dopant concentration, and forming a second semiconductor layer on the first semiconductor layer. The second semiconductor layer has a second dopant concentration that is less than the first dopant concentration. Ions are implanted into the second semiconductor layer to form an implanted region of the first conductivity type extending through the second semiconductor layer to contact the first semiconductor layer. A first electrode is formed on the implanted region of the second semiconductor layer, and a second electrode is formed on a non-implanted region of the second semiconductor layer. Related devices are also discussed.

Abstract: Methods of fabricating a semiconductor device include forming a first semiconductor layer of a first conductivity type and having a first dopant concentration, and forming a second semiconductor layer on the first semiconductor layer. The second semiconductor layer has a second dopant concentration that is less than the first dopant concentration. Ions are implanted into the second semiconductor layer to form an implanted region of the first conductivity type extending through the second semiconductor layer to contact the first semiconductor layer. A first electrode is formed on the implanted region of the second semiconductor layer, and a second electrode is formed on a non-implanted region of the second semiconductor layer. Related devices are also discussed.

Abstract: Group III Nitride based field effect transistor (FETs) are provided having a power degradation of less than about 3.0 dB when operated at a drain-to-source voltage (VDS) of about from about 28 to about 70 volts, a gate to source voltage (Vgs) of from about ?3.3 to about ?14 volts and a normal operating temperature for at least about 10 hours.

Abstract: Semiconductor device structures and methods of fabricating semiconductor devices structures are provided that include a semi-insulating or insulating GaN epitaxial layer on a conductive semiconductor substrate and/or a conductive layer. The semi-insulating or insulating GaN epitaxial layer has a thickness of at least about 4 ?m. GaN semiconductor device structures and methods of fabricating GaN semiconductor device structures are also provided that include an electrically conductive SiC substrate and an insulating or semi-insulating GaN epitaxial layer on the conductive SiC substrate. The GaN epitaxial layer has a thickness of at least about 4 ?m.

Abstract: Semiconductor device structures and methods of fabricating semiconductor devices structures are provided that include a semi-insulating or insulating GaN epitaxial layer on a conductive semiconductor substrate and/or a conductive layer. The semi-insulating or insulating GaN epitaxial layer has a thickness of at least about 4 ?m. GaN semiconductor device structures and methods of fabricating GaN semiconductor device structures are also provided that include an electrically conductive SiC substrate and an insulating or semi-insulating GaN epitaxial layer on the conductive SiC substrate. The GaN epitaxial layer has a thickness of at least about 4 ?m.

Abstract: A III-Nitride field-effect transistor, specifically a HEMT, comprises a channel layer, a barrier layer on the channel layer, an etch stop layer on the cap layer, a dielectric layer on the etch stop layer, a gate recess that extends to the barrier layer, and a gate contact in the gate recess. The etch stop layer may reduce damage associated with forming the recessed gate by not exposing the barrier layer to dry etching. The etch stop layer in the recess is removed and the remaining etch stop layer serves as a passivation layer.

Abstract: A monolithic electronic device includes a first nitride epitaxial structure including a plurality of nitride epitaxial layers. The plurality of nitride epitaxial layers include at least one common nitride epitaxial layer. A second nitride epitaxial structure is on the common nitride epitaxial layer of the first nitride epitaxial structure. A first plurality of electrical contacts is on the first epitaxial nitride structure and defines a first electronic device in the first nitride epitaxial structure. A second plurality of electrical contacts is on the first epitaxial nitride structure and defines a second electronic device in the second nitride epitaxial structure. A monolithic electronic device includes a bulk semi-insulating silicon carbide substrate having implanted source and drain regions and an implanted channel region between the source and drain regions, and a nitride epitaxial structure on the surface of the silicon carbide substrate. Corresponding methods are also disclosed.

Abstract: Methods of fabricating transistor in which a first Group III nitride layer is formed on a substrate in a reactor, and a second Group III nitride layer is formed on the first Group III nitride layer. An insulating layer such as, for example, a silicon nitride layer is formed on the second Group III nitride layer in-situ in the reactor. The substrate including the first Group III nitride layer, the second group III nitride layer and the silicon nitride layer is removed from the reactor, and the silicon nitride layer is patterned to form a first contact hole that exposes a first contact region of the second Group III nitride layer. A metal contact is formed on the first contact region of the second Group III nitride layer.

Abstract: Group III Nitride based field effect transistor (FETs) are provided having a power degradation of less than about 3.0 dB when operated at a drain-to-source voltage (VDS) of about from about 28 to about 70 volts, a gate to source voltage (Vgs) of from about ?3.3 to about ?14 volts and a normal operating temperature for at least about 10 hours.

Abstract: Group III Nitride based field effect transistor (FETs) are provided having a power degradation of less than about 3.0 dB when operated at a drain-to-source voltage (VDS) of about from about 28 to about 70 volts, a gate to source voltage (Vgs) of from about ?3.3 to about ?14 volts and a normal operating temperature for at least about 10 hours.

Abstract: Methods of forming Group III-nitride transistor device include forming a protective layer on a Group III-nitride semiconductor layer, forming a via hole through the protective layer to expose a portion of the Group III-nitride semiconductor layer, and forming a masking gate on the protective layer. The masking gate includes an upper portion having a width that is larger than a width of the via hole and having a lower portion extending into the via hole. The methods further include implanting source/drain regions in the Group III-nitride semiconductor layer using the masking gate as an implant mask.

Abstract: Transistors are fabricated by forming a protective layer having a first opening extending therethrough on a substrate, forming a dielectric layer on the protective layer having a second opening extending therethrough that is wider than the first opening, and forming a gate electrode in the first and second openings. A first portion of the gate electrode laterally extends on surface portions of the protective layer outside the first opening, and a second portion of the gate electrode is spaced apart from the protective layer and laterally extends beyond the first portion on portions of the dielectric layer outside the second opening. Related devices and fabrication methods are also discussed.