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Raleigh, NC, United States

In a method for making a GaN article, an epitaxial nitride layer is deposited on a single-crystal substrate. A 3D nucleation GaN layer is grown on the epitaxial nitride layer by HVPE under a substantially 3D growth mode. A GaN transitional layer is grown on the 3D nucleation layer by HVPE under a condition that changes the growth mode from the substantially 3D growth mode to a substantially 2D growth mode. A bulk GaN layer is grown on the transitional layer by HVPE under the substantially 2D growth mode. A polycrystalline GaN layer is grown on the bulk GaN layer to form a GaN/substrate bi-layer. The GaN/substrate bi-layer may be cooled from the growth temperature to an ambient temperature, wherein GaN material cracks laterally and separates from the substrate, forming a free-standing article.

Agency: Department of Defense | Branch: Navy | Program: STTR | Phase: Phase I | Award Amount: 80.00K | Year: 2015

Kyma will develop and model a modular high rep rate (>100kHz) photoconductive switch using GaN and commercial-off-the-shelf laser diodes. The switch will be designed to switch >1.5kV at >150A in 5-10ns.

Group III (Al, Ga, In)N single crystals, articles and films useful for producing optoelectronic devices (such as light emitting diodes (LEDs), laser diodes (LDs) and photodetectors) and electronic devices (such as high electron mobility transistors (HEMTs)) composed of III-V nitride compounds, and methods for fabricating such crystals, articles and films.

Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 1.00M | Year: 2014

The use of non-native substrates for GaN- based devices leads to devices with high densities of defects stemming from misfit dislocation formation due to lattice mismatch and large values of wafer bow stemming from thermal mismatch. The latter is particularly problematic as one attempts to grow device films on large area substrates. The high defect densities give rise to degraded performance and reliability, while the wafer bow can be problematic to device fabrication as well as to growth of e.g. InGaN at lower temperatures than underlying buffer layer temperatures, reducing device yields. The technology proposed utilizes HVPE films grown on both sides of the wafer, which results in a bow-free, thick GaN template which is scalable to large diameter substrates. Templates are polished to an epi-ready finish, which is only possible when the wafers are flat in the first place. We have demonstrated the FLAAT concept using 2 and 4 sapphire for GaN thicknesses up to 50 microns. Initial LED results yielded lower wavelength distribution across a wafer than a control layer directly on sapphire. Phase II of this program will improve the structural, optical, and electrical properties of the templates as well as demonstrate the concept at 6. We will additionally demonstrate the concept using AlN films instead of GaN films. Commercial Applications and Other Benefits: The technology can provide the quality of freestanding GaN at the cost of a GaN template so many types of devices can be impacted by the availability of the FLAAT templates. The large area sapphire market would grow if the technology takes off.

Agency: Department of Defense | Branch: Navy | Program: SBIR | Phase: Phase I | Award Amount: 80.00K | Year: 2015

Kyma Technologies proposes an innovative approach to grow device-quality single crystal GaN on polycrystalline diamond substrates. The result is a GaN-on-diamond template that can be inserted directly into a GaN FET epi process.

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