SBIR-STTR Award

Historically, hydride vapor phase epitaxy (HVPE) was the first technique to produce high quality thick GaN epitaxial layers. Resent progress in growing of multi-layer structure by HVPE in TDI make it possible to develop this technique to fabricate multi-layer GaN- AlxGa1-xN and AlxGa1-xN -AlyGa1-yN heterostructures for light emitting diodes (LEDs) in UV spectral range with operating wavelength up to 280 nm. Additionally, TDI is going to clarify possibility to growth AlGaN-based structure capable of 230 nm light emission. Currently, only metal organic vapor phase deposition is employed to III-V nitride devices production including light emitters and high-power microwave devices. HVPE is another epitaxial method known to deposit high quality GaN layers and AlGaN-GaN heterostructures. Recently, we demonstrated multilayer AlGaN/GaN/AlGaN p-n structures grown by this method on SiC substrates. Operated wavelength under current injection was varied from 340 to 350 nm. The results obtained give us opportunity to develop a new method of the AlGaN materials growth on sapphire substrates based on HVPE technology. Phase I objective is to prove the concept and demonstrate GaN-AlGaN structures grown on 2 inch sapphire by HVPE and suitable for UV LEDs fabrication. In the Phase II TDI will focus on the development of manufacturing technology for UV LED's.

The main goal for this project is to develop manufacturing technology for low defect substrate materials for high efficient UV light emitting devices based on group III nitride semiconductors. Three types of substrate materials are primary targets of this work: (1) AlGaN-on-sapphire templates, (2) AlN-on-SiC templates, and (3) free-standing AlGaN wafers. Proposed technical approach is based on hydride vapor phase epitaxial (HVPE) technology developed at TDI for GaN and AlN materials. In Phase I, TDI has demonstrated UV transparent AlGaN epitaxial materials grown by HVPE method. In Phase II, TDI will modify and develop specific versions of HVPE technology for each of the above substrate materials. Defect density reduction in these materials is the prime technical goal of the project. Grown materials will be delivered to DARPA and DARPA designated organizations for material evaluation and device fabrication. LOW DEFECT SUBSTRATES, ALGAN, ALN, UV SPECTRAL RANGE, LIGHT EMITTING DIODES, HYDRIDE VAPOR PHASE EPITAXY