TECHNOLOGY AREAS: Ground/Sea Vehicles, Electronics

OBJECTIVE: Design and develop high frequency, high efficiency solid state power switches

DESCRIPTION: Efficient power conversion and power conditioning devices significantly impact the mission capability and affordability of both the shipboard and airborne platforms through capacity considerations, generation cost and size and weight form factors.

The advancement of wide bandgap, planar Gallium Nitride (GaN) power device technology has demonstrated the advantage that can be gained by exploiting higher frequency in switch-mode power conversion where reduced passive element volume lead to lighter weight and reduced system costs. While significant progress has been made in normally�on devices(1), the normally-off devices preferred for many applications continue to lag in performance in planar GaN technology. An advance in normally-off planar device technology will enable simpler and more practical power systems for Navy applications.

The U.S. Navy is interested in investigating and developing planar normally-off devices that can sustain high breakdown and operating voltage (~1000 V) with at high power conversion frequencies (greater than 1MHz) and efficiency which will result in both reduced weight and volume power conversion systems and potentially enable active, dynamic, point-of-use load management power systems

The Navy will only fund proposals representing innovative R&D and involving technical risk.

PHASE I: Provide an initial development effort that demonstrates scientific merit and feasibility of an approach to achieving normally-off device operation. The effort will demonstrate a device that provides a blocking voltage of 1000 V, a threshold voltage >2.5 volts, with a specific on-resistance, RDS,ON-SP of 20 Ohm-mm. These specifications are to be achieved in a device geometry that is capable of comparable frequency response characteristics to current normally-on GaN power switching device (1).

PHASE II: Demonstrate a device with a 1 A drain current while advancing the blocking voltage to 1200 V, threshold voltage >5 V and reducing the on-resistance, RDS,ON-SP to 15 Ohm-mm. In addition the drain current collapse, RAC/RDC, at 600V, will be <3. Device yield on-wafer should be > 50%. Prototype packaged devices meeting the phase II goals will be delivered for testing and evaluation.

PHASE III: Demonstrate a device with a 5 A drain current with a blocking voltage to 1200 V, threshold voltage >5 V and reduced the on-resistance, RDS,ON-SP to 10 Ohm-mm. The reduce the drain current collapse, RAC/RDC, at 600V, to <1.5. Advance on-wafer yield to > 90%. Packaged devices meeting the phase III goals will be delivered for testing and evaluation.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Normally-off GaN devices will replace Silicon in most power applications where improved efficiency is required, which is currently a major drive in the commercial sector to reduce energy costs.

REFERENCES:
1. A 97.8% Efficient GaN HEMT Boost Converter With 300-W Output Power at 1 MHz, Yifeng Wu; Jacob-Mitos, M.; Moore, M.L.; Heikman, S., IEEE Electron Device Letters, Vol. 29, No. 8, Aug. 2008 Page(s):824 � 826.

2. "A 120-W boost converter operation using a high-voltage GaN HEMT, W. Saito, T. Nitta, Y. Kakiuchi, Y. Saito, K. Tsuda, I. Omura, and M. Yamaguchi", IEEE Electron Device Letters, Vol. 29, No.1, pp. 8-10, Jan 2008.

KEYWORDS: Power efficiency, Gallium Nitride, GaN