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Identification of the defect dominating high temperature reverse leakage current in vertical GaN power diodes through deep level transient spectroscopy

Applied Physics Letters

DasGupta, Sandeepan D.; Slobodyan, O.S.; Smith, Trevor S.; Binder, Andrew B.; Flicker, Jack D.; Kaplar, Robert K.; Mueller, Jacob M.; Garcia Rodriguez, Luciano A.; Atcitty, Stanley A.

Deep level defects in wide bandgap semiconductors, whose response times are in the range of power converter switching times, can have a significant effect on converter efficiency. Here, we use deep level transient spectroscopy (DLTS) to evaluate such defect levels in the n-drift layer of vertical gallium nitride (v-GaN) power diodes with VBD ~ 1500 V. DLTS reveals three energy levels that are at ~0.6 eV (highest density), ~0.27 eV (lowest density), and ~45 meV (a dopant level) from the conduction band. Dopant extraction from capacitance–voltage measurement tests (C–V) at multiple temperatures enables trap density evaluation, and the ~0.6 eV trap has a density of 1.2 × 1015 cm-3. The 0.6 eV energy level and its density are similar to a defect that is known to cause current collapse in GaN based surface conducting devices (like high electron mobility transistors). Analysis of reverse bias currents over temperature in the v-GaN diodes indicates a predominant role of the same defect in determining reverse leakage current at high temperatures, reducing switching efficiency.

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TYPE Journal Article YEAR 2022
OSTIDOI

GaN-based wide-bandgap power switching devices: From atoms to the grid

ECS Transactions

Atcitty, Stanley A.; Kaplar, Robert K.; DasGupta, Sandeepan D.; Marinella, Matthew J.; Armstrong, Andrew A.; Biedermann, Laura B.; Sun, Min; Palacios, Tomas; Smith, Mark A.

Emerging semiconductor switches based on the wide-bandgap semiconductor GaN have the potential to significantly improve the efficiency of portable power applications such as transportable energy storage. Such applications are likely to become more widespread as renewables such as wind and solar continue to come on-line. However, the long-term reliability of GaN-based power devices is relatively unexplored. In this paper, we describe joint work between Sandia National Laboratories and MIT on highvoltage AlGaN/GaN high electron mobility transistors. It is observed that the nature of current collapse is a strong function of bias conditions as well as device design, where factors such as Al composition in the barrier layer and surface passivation play a large role. Thermal and optical recovery experiments are performed to ascertain the nature of charge trapping in the device. Additionally, Kelvin-force microscopy measurements are used to evaluate the surface potential within the device. © The Electrochemical Society.

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TYPE Conference YEAR 2013
ScopusOSTI

Sub-bandgap light-induced carrier generation at room temperature in silicon carbide MOS capacitors

Materials Science Forum

DasGupta, Sandeepan D.; Armstrong, Andrew A.; Kaplar, Robert K.; Marinella, Matthew J.; Brock, Reinhard; Smith, Mark A.; Atcitty, Stanley A.

Carrier generation characteristics in n-type substrate SiC MOS capacitors induced by sub-bandgap energy light are reported. The generation rate is high enough to create an inversion layer in ∼20 minutes with monochromatic light (front side illumination) of energy 2.1 eV (intensity ∼5×10 16 cm-2s-1) in 4H-SiC for electric fields smaller than 1 MV/cm. Generation and recovery results strongly indicate involvement of a metastable defect whose efficiency as a generation center increases under hole-rich and decreases under electron-rich conditions. The generation dependence on bias history and light energy shows the defect to have properties consistent with the metastable silicon vacancy / carbon vacancy-antisite complex (VSi/Vc-CSi). © (2012) Trans Tech Publications.

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TYPE Conference YEAR 2012
ScopusOSTI

High power semiconductor devices for facts: Current state of the art and opportunities for advanced materials

ECS Transactions

Marinella, M.J.; Atcitty, Stanley A.; DasGupta, Sandeepan D.; Kaplar, Robert K.; Smith, Mark A.

Flexible AC Transmission Systems (FACTS) use advanced power electronics to minimize reactive power loss on the grid. Power devices used in FACTS systems must be capable of switching several thousand amps at voltages of 1-10 kV. Traditionally, these systems have relied on silicon thyristors, but recently have also began to incorporate insulated gate bipolar transistors. FACTS systems present an opportunity for emerging SiC and GaN power transistors, which offer major efficiency gains. However, for these advanced materials to be considered for use in high consequence grid level systems like FACTS controllers, excellent reliability must be demonstrated. ©The Electrochemical Society.

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TYPE Conference YEAR 2011
ScopusOSTI
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25 Results