Abstract: Methods for manufacturing semiconductor wafer structures are described which exhibit improved lifetime and reliability. The methods comprise transferring an active semiconductor layer structure from a native non-lattice-matched semiconductor growth substrate to a working substrate, wherein strain-matching layers, and optionally a portion of the active semiconductor layer structure, are removed. In certain embodiment, the process of attaching the active semiconductor layer structure to the working substrate includes annealing at an elevated temperature for a specified time.

Abstract: A high voltage and high power gallium nitride (GaN) transistor structure is disclosed. A plurality of structural epitaxial layers including a GaN buffer layer is deposited on a substrate. A GaN termination layer is deposited on the plurality of structural epitaxial layers. The GaN termination layer is adapted to protect the plurality of structural epitaxial layers from surface reactions. The GaN termination layer is sufficiently thin to allow electrons to tunnel through the GaN termination layer. Electrical contacts are deposited on the GaN termination layer, thereby forming a high electron mobility transistor.

Abstract: The present invention relates to a high voltage and high power gallium nitride (GaN) transistor structure. In general, the GaN transistor structure includes a sub-buffer layer that serves to prevent injection of electrons into a substrate during high voltage operation, thereby improving performance of the GaN transistor structure during high voltage operation. Preferably, the sub-buffer layer is aluminum nitride, and the GaN transistor structure further includes a transitional layer, a GaN buffer layer, and an aluminum gallium nitride Schottky layer.

Abstract: The present invention relates to passivation of a gallium nitride (GaN) structure before the GaN structure is removed from an epitaxial growth chamber. The GaN structure includes one or more structural epitaxial layers deposited on a substrate, and the passivation layer deposited on the structural epitaxial layers. In general, the passivation layer is a dielectric material deposited on the GaN structure that serves to passivate surface traps on the surface of the structural epitaxial layers. Preferably, the passivation layer is a dense, thermally deposited silicon nitride passivation layer.

Abstract: Bulk single crystals of AlN having a diameter greater than about 25 mm and dislocation densities of about 10,000 cm?2 or less and high-quality AlN substrates having surfaces of any desired crystallographic orientation fabricated from these bulk crystals.

Abstract: A single step process for nucleation and subsequent epitaxial growth on a lattice mismatched substrate is achieved by pre-treating the substrate surface with at least one group III reactant or at least one group II reactant prior to the introduction of a group V reactant or a group VI reactant. The group III reactant or the group II reactant is introduced into a growth chamber at an elevated growth temperature to wet a substrate surface prior to any actual crystal growth. Once the pre-treatment of the surface is complete, a group V reactant or a group VI reactant is introduced to the growth chamber to commence the deposition of a nucleation layer. A buffer layer is then grown on the nucleation layer providing a surface upon which the epitaxial layer is grown preferably without changing the temperature within the chamber.

Abstract: The present invention relates to passivation of a gallium nitride (GaN) structure before the GaN structure is removed from an epitaxial growth chamber. The GaN structure includes one or more structural epitaxial layers deposited on a substrate, and the passivation layer deposited on the structural epitaxial layers. In general, the passivation layer is a dielectric material deposited on the GaN structure that serves to passivate surface traps on the surface of the structural epitaxial layers. Preferably, the passivation layer is a dense, thermally deposited silicon nitride passivation layer.

Abstract: The present invention relates to an epitaxial structure having one or more structural epitaxial layers, including a gallium nitride (GaN) layer, which is deposited on a substrate, and a method of growing the epitaxial structure, wherein the structural epitaxial layers can be separated from the substrate. In general, a sacrificial epitaxial layer is deposited on the substrate between the substrate and the structural epitaxial layers, and the structural epitaxial layers are deposited on the sacrificial layer. After growth, the structural epitaxial layers are separated from the substrate by oxidizing the sacrificial layer. The structural epitaxial layers include a nucleation layer deposited on the sacrificial layer and a gallium nitride layer deposited on the nucleation layer. Optionally, the oxidation of the sacrificial layer may also oxidize the nucleation layer.

Abstract: The present invention relates to a high voltage and high power gallium nitride (GaN) transistor structure. In general, the GaN transistor structure includes a sub-buffer layer that serves to prevent injection of electrons into a substrate during high voltage operation, thereby improving performance of the GaN transistor structure during high voltage operation. Preferably, the sub-buffer layer is aluminum nitride, and the GaN transistor structure further includes a transitional layer, a GaN buffer layer, and an aluminum gallium nitride Schottky layer.