The demand for high power switches for various classical and renewable energy applications is increasing exponentially. The proposed research will provide for a transformative and disruptive technology for power electronics that will go well beyond classical semiconductor materials limits and lead to unprecedented switching power densities and reliability beyond the Si-based technology. The successful demonstration of such disruptive technology would revolutionize energy switching and transmission, energy storage, and related applications in electrical motor drives and other power-intensive applications. This research will have a direct impact on the materials and devices that will be used for applications that deal with the preservation and extension of natural resources by allowing for an efficient use and transmission of electrical energy, availability of clean potable water through disinfection by the use of UV, and the detection of pollutants and other effluents. This program will provide the opportunity to educate the next generation of engineers capable of out-of-the-box thinking and will support one PhD student, and a part-time undergraduate assistant and post-doctoral researcher. The novel concepts developed within this project will be implemented in the educational and outreach efforts, especially integrating characterization and process control schemes to applications dealing with materials needed for sustainability, preservation and extension of our natural resources.
Current GaN-based power device designs focus on simple Schottky and p-i-n diodes. New technological breakthroughs are needed that are not limited by the classical materials figure of merit. Superjunctions are lateral devices that surpass the materials figure of merit limit by attaining full compensation under the reverse bias and very low on-resistance under the forward bias, i.e., they behave as dielectrics in one direction and as conductors in the other. Although Si-based superjunctions are a mature technology, known as CoolMos, no superjunctions have been attempted in wide bandgap materials because of the exceptional technological challenges. Recent technological advances in the growth of lateral polar structures and newly developed doping control schemes bridge the missing technological gap and provide a new path for GaN-based superjunction technology that does not rely on re-growth and ion implantation technologies, which have been unsuccessful in III-nitrides although they are routinely used in the Si technology. These devices will eventually allow for significant breakdown voltages exceeding 5 kV and low on-resistance. This research will establish growth technology for both, vertical n-type and p-type thick drift region junctions based on controllable, simultaneous growth of N-polar and Ga-polar GaN domains, with the associated low doping levels in the range of 10'16 to 10'17 cm-3 for complete depletion. The ability to grow and to control doping in p- and n-doped domains side-by-side will establish a pathway for the design of superjunction device structures and demonstrate superjunctions with breakdown voltages exceeding 1200 V and 500% better performance than predicted by the Baliga's figure of merit. Furthermore, this research will provide a transformative and disruptive technology for a new generation of devices whose architecture is not limited by the classical growth and processing approaches.
