Publications Search

This project is part of a multi-lab consortium that leverages U.S. research expertise and facilities at national labs and universities to significantly advance electric drive power density and reliability, while simultaneously reducing cost. The final objective of the consortium is to develop a 100 kW traction drive system that achieves 33 kW/L, has an operational life of 300,000 miles, and a cost of less than $\$6$/kW. One element of the system is a 100 kW inverter with a power density of 100 kW/L and a cost of $\$2.7$/kW. New materials such as widebandgap semiconductors, soft magnetic materials, and ceramic dielectrics, integrated using multi-objective cooptimization design techniques, will be utilized to achieve these program goals. This project focuses on a subset of the power electronics work within the consortium, specifically the design, fabrication, and evaluation of vertical GaN power devices suitable for automotive applications.

More Details

TYPE Other Report YEAR 2018

DOI OSTI

Investigation of interfacial impurities in m-plane GaN regrown p-n junctions for high-power vertical electronic devices

Proceedings of SPIE - The International Society for Optical Engineering

Stricklin, Isaac; Monavarian, Morteza; Aragon, Andrew; Pickrell, Gregory P.; Crawford, Mary H.; Allerman, A.A.; Armstrong, Andrew A.; Feezell, Daniel F.

GaN is an attractive material for high-power electronics due to its wide bandgap and large breakdown field. Verticalgeometry devices are of interest due to their high blocking voltage and small form factor. One challenge for realizing complex vertical devices is the regrowth of low-leakage-current p-n junctions within selectively defined regions of the wafer. Presently, regrown p-n junctions exhibit higher leakage current than continuously grown p-n junctions, possibly due to impurity incorporation at the regrowth interfaces, which consist of c-plane and non-basal planes. Here, we study the interfacial impurity incorporation induced by various growth interruptions and regrowth conditions on m-plane p-n junctions on free-standing GaN substrates. The following interruption types were investigated: (1) sample in the main MOCVD chamber for 10 min, (2) sample in the MOCVD load lock for 10 min, (3) sample outside the MOCVD for 10 min, and (4) sample outside the MOCVD for one week. Regrowth after the interruptions was performed on two different samples under n-GaN and p-GaN growth conditions, respectively. Secondary ion mass spectrometry (SIMS) analysis indicated interfacial silicon spikes with concentrations ranging from 5e16 cm^-3 to 2e18 cm^-3 for the n-GaN growth conditions and 2e16 cm^-3 to 5e18 cm-3 for the p-GaN growth conditions. Oxygen spikes with concentrations ~1e17 cm^-3 were observed at the regrowth interfaces. Carbon impurity levels did not spike at the regrowth interfaces under either set of growth conditions. We have correlated the effects of these interfacial impurities with the reverse leakage current and breakdown voltage of regrown m-plane p-n junctions.

More Details

TYPE Journal Article YEAR 2018

DOI OSTI

Advanced GaN Device Technologies for Power Electronics

Pickrell, Gregory P.; Armstrong, Andrew A.; Allerman, A.A.; Crawford, Mary H.; Feezell, D.; Monavarian, M.; Aragon, A.; Zutavern, Fred J.; Mar, Alan M.; Schrock, Emily A.; Flicker, Jack D.; Delhotal, Jarod J.; Teague, J.D.; Lehr, J.M.; Cross, K.C.; Glaser, Caleb E.; Van Heukelom, Michael V.; Gallegos, Richard J.; Bigman, Verle H.; Kaplar, Robert K.

Abstract not provided.

More Details

TYPE Conference Poster YEAR 2018

OSTI

Highly Efficient Solar-Blind Single Photon Detectors

Armstrong, Andrew A.; Klein, Brianna A.; Allerman, A.A.; Baca, A.G.; Crawford, Mary H.; Pickrell, Gregory P.; Perez, Carlos P.; Podkaminer, Jacob; Siegal, Michael P.; Jayawardena, Asanka; Ahyi, Ayayi; Dhar, Sarit

Photodetectors sensitive to the ultra-violet spectrum were demonstrated using an AlGaN high electron mobility transistor with an GaN nanodot optical floating gate. Peak responsivity of 2 x 10⁹ A/W was achieved with a gain-bandwidth product > 1 GHz at a cut-on energy of 4.10 eV. Similar devices exhibited visible-blind rejection ratios > 10⁶. The photodetection mechanism for $β$-Ga₂O₃ was also investigated. It was concluded that Schottky barrier lowering by self-trapped holes enables photodetector gain.

More Details

TYPE SAND Report YEAR 2018

DOI OSTI