Abstract: High electron mobility transistors and/or methods of fabricating high electron mobility transistors that include a first Group III-nitride layer having vertically grown regions, laterally grown regions and a coalescence region are provided. A Group III-nitride channel layer is provided on the first Group III-nitride layer and a Group III-nitride barrier layer is provided on the Group III-nitride channel layer. A drain contact, a source contact and a gate contact are provided on the barrier layer. The gate contact is disposed on a portion of the barrier layer on a laterally grown region of the first Group III-nitride layer and at least a portion of one of the source contact and/or the drain contact is disposed on a portion of the barrier layer on a vertically grown region of the first Group III-nitride layer.

Abstract: A structure is disclosed that reduces the forward voltage across the interface between silicon carbide and Group III nitride layers. The structure includes a conductive silicon carbide substrate and a conductive layer of aluminum gallium nitride on the silicon carbide substrate. The aluminum gallium nitride layer has a mole fraction of aluminum that is sufficient to bring the conduction bands of the silicon carbide substrate and the aluminum gallium nitride into close proximity, but less than a mole fraction of aluminum that would render the aluminum gallium nitride layer resistive.

Abstract: Group III-Nitride semiconductor device structures and methods of fabricating Group III-Nitride structures are provided that include an electrically conductive Group III-Nitride substrate, such as a GaN substrate, and a semi-insulating or insulating Group III-Nitride epitaxial layer, such as a GaN epitaxial layer, on the electrically conductive Group III-Nitride substrate. The Group III-Nitride epitaxial layer has a lattice constant that is and a composition that may be substantially the same as a composition and a lattice constant of the Group III-Nitride substrate.

Abstract: Aluminum free high electron mobility transistors (HEMTs) and methods of fabricating aluminum free HEMTs are provided. In some embodiments, the aluminum free HEMTs include an aluminum free Group III-nitride barrier layer, an aluminum free Group III-nitride channel layer on the barrier layer and an aluminum free Group III-nitride cap layer on the channel layer.

Abstract: A high power, wide-bandgap device is disclosed that exhibits reduced junction temperature and higher power density during operation and improved reliability at a rated power density. The device includes a diamond substrate for providing a heat sink with a thermal conductivity greater than silicon carbide, a single crystal silicon carbide layer on the diamond substrate for providing a supporting crystal lattice match for wide-bandgap material structures that is better than the crystal lattice match of diamond, and a Group III nitride heterostructure on the single crystal silicon carbide layer for providing device characteristics.

Abstract: A heterojunction transistor may include a channel layer comprising a Group III nitride, a barrier layer comprising a Group III nitride on the channel layer, and an energy barrier comprising a layer of a Group III nitride including indium on the channel layer such that the channel layer is between the barrier layer and the energy barrier. The barrier layer may have a bandgap greater than a bandgap of the channel layer, and a concentration of indium (In) in the energy barrier may be greater than a concentration of indium (In) in the channel layer. Related methods are also discussed.

Abstract: A high power, wide-bandgap device is disclosed that exhibits reduced junction temperature and higher power density during operation and improved reliability at a rated power density. The device includes a diamond substrate for providing a heat sink with a thermal conductivity greater than silicon carbide, a single crystal silicon carbide layer on the diamond substrate for providing a supporting crystal lattice match for wide-bandgap material structures that is better than the crystal lattice match of diamond, and a Group III nitride heterostructure on the single crystal silicon carbide layer for providing device characteristics.

Abstract: Contacts for a nitride based transistor and methods of fabricating such contacts provide a recess through a regrowth process. The contacts are formed in the recess. The regrowth process includes fabricating a first cap layer comprising a Group III-nitride semiconductor material. A mask is fabricated and patterned on the first cap layer. The pattern of the mask corresponds to the pattern of the recesses for the contacts. A second cap layer comprising a Group III-nitride semiconductor material is selectively fabricated (e.g. grown) on the first cap layer utilizing the patterned mask. Additional layers may also be formed on the second cap layer. The mask may be removed to provide recess(es) to the first cap layer, and contact(s) may be formed in the recess(es). Alternatively, the mask may comprise a conductive material upon which a contact may be formed, and may not require removal.

Abstract: Binary Group III-nitride high electron mobility transistors (HEMTs) and methods of fabricating binary Group III-nitride HEMTs are provided. In some embodiments, the binary Group III-nitride HEMTs include a first binary Group III-nitride barrier layer, a binary Group III-nitride channel layer on the first barrier layer; and a second binary Group III-nitride barrier layer on the channel layer. In some embodiments, the binary Group III-nitride HEMTs include a first AIN barrier layer, a GaN channel layer and a second AIN barrier 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: High electron mobility transistors are provided that include a non-uniform aluminum concentration AlGaN based cap layer having a high aluminum concentration adjacent a surface of the cap layer that is remote from the barrier layer on which the cap layer is provided. High electron mobility transistors are provided that include a cap layer having a doped region adjacent a surface of the cap layer that is remote from the barrier layer on which the cap layer is provided. Graphitic BN passivation structures for wide bandgap semiconductor devices are provided. SiC passivation structures for Group III-nitride semiconductor devices are provided. Oxygen anneals of passivation structures are also provided. Ohmic contacts without a recess are also provided.

Abstract: Transistors and/or methods of fabricating transistors that include a source contact, drain contact and gate contact are provided. In some embodiments, a channel region is provided between the source and drain contacts and at least a portion of the channel regions includes a hybrid layer comprising semiconductor material. In particular embodiments of the present invention, the transistor is a current aperture transistor. The channel region may include pendeo-epitaxial layers or epitaxial laterally overgrown layers. Transistors and methods of fabricating current aperture transistors that include a trench that extends through the channel and barrier layers and includes semiconductor material therein are also provided.

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 56 volts, a gate to source voltage (Vgs) of from about ?8 to about ?14 volts and a temperature of about 140° C. for at least about 10 hours.

Abstract: A semiconductor structure is disclosed that includes a silicon carbide wafer having a diameter of at least 100 mm with a Group III nitride heterostructure on the wafer that exhibits high uniformity in a number of characteristics. These include: a standard deviation in sheet resistivity across the wafer less than three percent; a standard deviation in electron mobility across the wafer of less than 1 percent; a standard deviation in carrier density across the wafer of no more than about 3.3 percent; and a standard deviation in conductivity across the wafer of about 2.5 percent.

Abstract: High electron mobility transistors are provided that include a non-uniform aluminum concentration AlGaN based cap layer having a high aluminum concentration adjacent a surface of the cap layer that is remote from the barrier layer on which the cap layer is provided. High electron mobility transistors are provided that include a cap layer having a doped region adjacent a surface of the cap layer that is remote from the barrier layer on which the cap layer is provided. Graphitic BN passivation structures for wide bandgap semiconductor devices are provided. SiC passivation structures for Group III-nitride semiconductor devices are provided. Oxygen anneals of passivation structures are also provided. Ohmic contacts without a recess are also provided.

Abstract: Semi-insulating Group III nitride layers and methods of fabricating semi-insulating Group III nitride layers include doping a Group III nitride layer with a shallow level p-type dopant and doping the Group III nitride layer with a deep level dopant, such as a deep level transition metal dopant. Such layers and/or method may also include doping a Group III nitride layer with a shallow level dopant having a concentration of less than about 1×1017 cm?3 and doping the Group III nitride layer with a deep level transition metal dopant. The concentration of the deep level transition metal dopant is greater than a concentration of the shallow level p-type dopant.

Abstract: Transistor fabrication includes forming a nitride-based channel layer on a substrate, forming a barrier layer on the nitride-based channel layer, forming a contact recess in the barrier layer to expose a contact region of the nitride-based channel layer, forming a contact layer on the exposed contact region of the nitride-based channel layer, for example, using a low temperature deposition process, forming an ohmic contact on the contact layer and forming a gate contact disposed on the barrier layer adjacent the ohmic contact. A high electron mobility transistor (HEMT) and methods of fabricating a HEMT are also provided.

Abstract: A semiconductor structure includes a substrate, a nucleation layer on the substrate, a compositionally graded layer on the nucleation layer, and a layer of a nitride semiconductor material on the compositionally graded layer. The layer of nitride semiconductor material includes a plurality of substantially relaxed nitride interlayers spaced apart within the layer of nitride semiconductor material. The substantially relaxed nitride interlayers include aluminum and gallium and are conductively doped with an n-type dopant, and the layer of nitride semiconductor material including the plurality of nitride interlayers has a total thickness of at least about 2.0 ?m.

Abstract: A semiconductor structure includes a first layer of a nitride semiconductor material, a substantially unstrained nitride interlayer on the first layer of nitride semiconductor material, and a second layer of a nitride semiconductor material on the nitride interlayer. The nitride interlayer has a first lattice constant and may include aluminum and gallium and may be conductively doped with an n-type dopant. The first layer and the second layer together have a thickness of at least about 0.5 ?m. The nitride semiconductor material may have a second lattice constant, such that the first layer may be more tensile strained on one side of the nitride interlayer than the second layer may be on the other side of the nitride interlayer.

Abstract: A semiconductor structure is disclosed that includes a silicon carbide wafer having a diameter of at least 100 mm with a Group III nitride heterostructure on the wafer that exhibits high uniformity in a number of characteristics. These include: a standard deviation in sheet resistivity across the wafer less than three percent; a standard deviation in electron mobility across the wafer of less than 1 percent; a standard deviation in carrier density across the wafer of no more than about 3.3 percent; and a standard deviation in conductivity across the wafer of about 2.5 percent.