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Evaluation of a 'Field Cage' for Electric Field Control in GaN-Based HEMTs That Extends the Scalability of Breakdown into the kV Regime

IEEE Transactions on Electron Devices

Tierney, Brian D.; Dickerson, Jeramy R.; Reza, Shahed R.; Kaplar, Robert K.; Baca, A.G.; Marinella, Matthew J.

A distributed impedance 'field cage' structure is proposed and evaluated for electric field control in GaN-based, lateral high electron mobility transistors operating as kilovolt-range power devices. In this structure, a resistive voltage divider is used to control the electric field throughout the active region. The structure complements earlier proposals utilizing floating field plates that did not employ resistively connected elements. Transient results, not previously reported for field plate schemes using either floating or resistively connected field plates, are presented for ramps of dVds/dt = 100 V/ns. For both dc and transient results, the voltage between the gate and drain is laterally distributed, ensuring that the electric field profile between the gate and drain remains below the critical breakdown field as the source-to-drain voltage is increased. Our scheme indicates promise for achieving the breakdown voltage scalability to a few kilovolts.

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TYPE Journal Article YEAR 2017
DOIOSTIScopusDOIOSTIScopus

Imaging the Impact of Proton Irradiation on Edge Terminations in Vertical GaN pin Diodes

IEEE Electron Device Letters

Celio, Kimberlee C.; King, Michael P.; Dickerson, Jeramy R.; Vizkelethy, Gyorgy V.; Armstrong, Andrew A.; Fischer, Arthur J.; Allerman, A.A.; Kaplar, Robert K.; Aktas, Ozgur; Kizilyalli, Isik C.; Talin, A.A.; Leonard, Francois L.

Devices based on GaN have shown great promise for high power electronics, including their potential use as radiation tolerant components. An important step to realizing high power diodes is the design and implementation of an edge termination to mitigate field crowding, which can lead to premature breakdown. However, little is known about the effects of radiation on edge termination functionality. We experimentally examine the effects of proton irradiation on multiple field ring edge terminations in high power vertical GaN pin diodes using in operando imaging with electron beam induced current (EBIC). We find that exposure to proton irradiation influences field spreading in the edge termination as well as carrier transport near the anode. By using depth-dependent EBIC measurements of hole diffusion length in homoepitaxial n-GaN we demonstrate that the carrier transport effect is due to a reduction in hole diffusion length following proton irradiation.

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TYPE Journal Article YEAR 2017
DOIOSTI

Module-level paralleling of vertical GaN PiN diodes

WiPDA 2016 - 4th IEEE Workshop on Wide Bandgap Power Devices and Applications

Flicker, Jack D.; Brocato, Robert W.; Delhotal, Jarod J.; Neely, Jason C.; Sumner, Bjorn; Dickerson, Jeramy R.; Kaplar, Robert K.

The effects of paralleling low-current vertical Gallium Nitride (v-GaN) diodes in a custom power module are reported. Four paralleled v-GaN diodes were demonstrated to operate in a buck converter at 1.3 Apeak (792 mArms) at 240 V and 15 kHz switching frequency. Additionally, high-fidelity SPICE simulations demonstrate the effects of device parameter variation on power sharing in a power module. The device parameters studied were found to have a sub-linear relationship with power sharing, indicating a relaxed need to bin parts for paralleling. This result is very encouraging for power electronics based on low-current v-GaN and demonstrates its potential for use in high-power systems.

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TYPE Conference Poster YEAR 2016
DOIOSTIScopusDOIOSTIScopus

Review—Ultra-Wide-Bandgap AlGaN Power Electronic Devices

ECS Journal of Solid State Science and Technology

Kaplar, Robert K.; Allerman, A.A.; Armstrong, Andrew A.; Crawford, Mary H.; Dickerson, Jeramy R.; Fischer, Arthur J.; Baca, A.G.; Douglas, Erica A.

“Ultra” wide-bandgap semiconductors are an emerging class of materials with bandgaps greater than that of gallium nitride (EG > 3.4 eV) that may ultimately benefit a wide range of applications, including switching power conversion, pulsed power, RF electronics, UV optoelectronics, and quantum information. This paper describes the progress made to date at Sandia National Laboratories to develop one of these materials, aluminum gallium nitride, targeted toward high-power devices. The advantageous material properties of AlGaN are reviewed, questions concerning epitaxial growth and defect physics are covered, and the processing and performance of vertical- and lateral-geometry devices are described. The paper concludes with an assessment of the outlook for AlGaN, including outstanding research opportunities and a brief discussion of other potential applications.

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TYPE Journal Article YEAR 2016
DOIOSTIDOIOSTI

Identification of the primary compensating defect level responsible for determining blocking voltage of vertical GaN power diodes

Applied Physics Letters

King, Michael P.; Kaplar, Robert K.; Dickerson, Jeramy R.; Lee, Stephen R.; Allerman, A.A.; Crawford, Mary H.; Marinella, Matthew J.; Flicker, Jack D.; Fleming, Robert M.; Kizilyalli, I.C.; Aktas, O.; Armstrong, Andrew A.

Electrical performance and characterization of deep levels in vertical GaN P-i-N diodes grown on low threading dislocation density (∼104 - 106cm-2) bulk GaN substrates are investigated. The lightly doped n drift region of these devices is observed to be highly compensated by several prominent deep levels detected using deep level optical spectroscopy at Ec-2.13, 2.92, and 3.2 eV. A combination of steady-state photocapacitance and lighted capacitance-voltage profiling indicates the concentrations of these deep levels to be Nt = 3 × 1012, 2 × 1015, and 5 × 1014cm-3, respectively. The Ec-2.92 eV level is observed to be the primary compensating defect in as-grown n-type metal-organic chemical vapor deposition GaN, indicating this level acts as a limiting factor for achieving controllably low doping. The device blocking voltage should increase if compensating defects reduce the free carrier concentration of the n drift region. Understanding the incorporation of as-grown and native defects in thick n-GaN is essential for enabling large VBD in the next-generation wide-bandgap power semiconductor devices. Thus, controlling the as-grown defects induced by epitaxial growth conditions is critical to achieve blocking voltage capability above 5 kV.

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TYPE Journal Article YEAR 2016
DOIOSTIScopus
Results 51–75 of 104
Results 51–75 of 104