1.2 kV class GaN on GaN vertical U-MOSFET with reach through protection and shielding by Mg implantation

C56-20a-273160Machine driven processes such as pumps, fans, compressed air, and materials handling and processing accounted for 68% of electricity use (2,840 TBtu direct use) by U.S. manufacturing in 2010 (DoE 2014). Many of the involved electric motors use existing silicon diode-based switches for power conversion. Replacing these Si- or even the more recent SiC-based switches could unlock a potential to reduce power losses and save hundreds of GWh/year and billions of dollars. More potential savings are possible considering the ongoing spread of electric cars and the number of adjustable speed drive (ASD) motor systems in the US being expected to double in the next decade. To unlock the savings potential in ASD motor systems, we will develop the first 1.3 kV-class gallium nitride (GaN)-based trench MOSFET diodes using ion implantation for shielding. Demonstration of such devices will enable the integration of these devices to form a low loss power supply (Figure 1). This will result in superior efficiency and temperature stability, relaxed requirements for system cooling that complicate packaging, as well as reduced size, volume and weight compared to current technologies. The novel GaN trench MOSFETs are enabled by recent breakthroughs on the materials side that now need to be transferred to the device side. For the realization of the proposed devices, we will bring about innovations at all technological levels by advancing n- and p-type doping, device design and fabrication, and packaging. In this project, we will demonstrate GaN-based UMOSFET diodes with shielding using a novel ion implantation process developed in previous ARPA-E-funded projects.(Breckenridge 2021) Feasibility of MOSFETs with capabilities of 1.3 kV blocking voltage, forward current density of ~1 kA/cm2, Ron < 1 m? cm2, and a reasonable threshold voltage (3.5 V to 7 V) will be demonstrated at the end of Phase I and a prototype with 100 A current extraction with a clear pathway for scaleup at the end of Phase II will be presented. The immediate targeted application of these GaN MOSFETs is for ASD motor system and the developed devices will replace Si and SiC based switches to achieve very high efficiency power conversion. The existing and competing wide bandgap SiC is limited by poor on-resistance >2 m?cm2 due to low channel mobilities. The low channel mobilities also limit the switching performance. Consequently, the proposed GaN- based UMOSFET is expected to showcase more than a 2X improvement in specific on resistance, leading to high efficiency power conversion in addition to better switching performance due to higher channel mobilities. In general, these devices will help target applications with the need for efficient and compact power conversion.