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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

Band offsets of La2O3 on (0001) GaN grown by reactive molecular-beam epitaxy

Applied Physics Letters

Ihlefeld, Jon I.; Brumbach, Michael T.; Atcitty, Stanley A.

La2O3 films were prepared on (0001)-oriented GaN substrates via reactive molecular-beam epitaxy. Film orientation and phase were assessed using reflection high-energy electron and X-ray diffraction. Films were observed to grow as predominantly hexagonal La2O3 for thicknesses less than 10 nm while film thickness greater than 10 nm favored mixed cubic and hexagonal symmetries. Band offsets were characterized by X-ray photoelectron spectroscopy on hexagonally symmetric films and valence band offsets of 0.63 ± 0.04 eV at the La2O3/GaN interface were measured. A conduction band offset of approximately 1.5 eV could be inferred from the measured valence band offset.

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TYPE Journal Article YEAR 2013
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Impact of the Al mole fraction in the bulk- and surface-state induced instability of AlGaN/GaN HEMTs

Materials Research Society Symposium Proceedings

DasGupta, S.; Sun, M.; Armstrong, Andrew A.; Kaplar, Robert K.; Marinella, M.; Stanley, James B.; Smith, Mark A.; Atcitty, Stanley A.; Palacios, T.

Charge trapping and slow (10 s to > 1000 s) detrapping in AlGaN/GaN HEMTs designed for high breakdown voltage (> 1500 V) are studied to identify the impact of Al molefraction and passivation on trapping. Two different trapping components, TG1 (E a = 0.62 eV) and TG2 (with negligible temperature dependence) in AlGaN dominate under gale bias stress in the off-state. Al 0.15Ga 0.85N shows much more vulnerability to trapping under gate stress in the absence of passivation than does AlGaN with a higher Al mole fraction. Under large drain bias, trapping is dominated by a much deeper trap TD. Detrapping under illumination by monochromatic light shows TD to have E a ≈ 1.65 eV in Al 0.26Ga 0.74N and E a ≈ 1.85 eV in Al 0.15Ga 0.85N. This is consistent with a transition from a deep state (E c - 2.0 eV) in the AlGaN barrier to the 2DEG. © 2012 Materials Research Society.

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TYPE Conference YEAR 2012
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Slow detrapping transients due to gate and drain bias stress in high breakdown voltage AlGaN/GaN HEMTs

IEEE Transactions on Electron Devices

Dasgupta, Sandeepan; Sun, Min; Armstrong, Andrew A.; Kaplar, Robert K.; Marinella, Matthew J.; Stanley, James B.; Atcitty, Stanley A.; Palacios, Tomas

Charge trapping and slow (from 10 s to > 1000 s) detrapping in AlGaN/GaN high electron mobility transistors (HEMTs) designed for high breakdown voltages (> 1500 V) is studied through a combination of electrical, thermal, and optical methods to identify the impact of Al molefraction and passivation on trapping. Trapping due to 5-10 V drain bias stress in the on-state (V gs = 0) is found to have significantly slower recovery, compared with trapping in the off-state (V gs < V th, V ds = 0). Two different trapping components, i.e., TG1 (E a = 0.6 eV) and TG2 (with negligible temperature dependence), in AlGaN dominate under gate bias stress in the off-state. Al 0.15 Ga 0.85N shows much more vulnerability to trapping under gate stress in the absence of passivation than does AlGaN with a higher Al mole fraction. Under large drain bias, trapping is dominated by a much deeper trap TD. Detrapping under monochromatic light shows TD to have E a ≈ 1.65 eV. Carbon doping in the buffer is shown to introduce threshold voltage shifts, unlike any of the other traps. © 2012 IEEE.

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TYPE Journal Article YEAR 2012
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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
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Empirical battery model characterizing a utility-scale carbon-enhanced VRLA battery

IEEE Energy Conversion Congress and Exposition: Energy Conversion Innovation for a Clean Energy Future, ECCE 2011, Proceedings

Fregosi, Daniel; Bhattacharya, Subhashish; Atcitty, Stanley A.

In this paper, the electrical characteristics of a carbon enhanced valve-regulated lead-acid (VRLA) battery from East Penn Manufacturing are investigated and a dynamic model is developed for use in electrical simulations. The electrochemical processes that cause specific dynamic behaviors have been investigated. These processes are explained and a non-linear electric model, which captures the results of some of these electrochemical dynamics, is presented. The method to determine model parameters using experimental data is shown. To verify the battery model, both a pulsed current profile and an arbitrary current profile were applied to the battery and to the battery model and the voltage responses of the two were compared. © 2011 IEEE.

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TYPE Conference YEAR 2011
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Sub-bandgap light-induced carrier generation at room temperature in 4H-SiC metal oxide semiconductor capacitors

Applied Physics Letters

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

Carrier generation characteristics in n-type substrate silicon carbide (SiC) metal oxide semiconductor capacitors induced by sub-bandgap energy light are reported. The generation rate is high enough to create an inversion layer in approximately 20 min with monochromatic front side illumination of energy 2.1 eV in 4H-SiC for electric fields less 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-C Si). © 2011 American Institute of Physics.

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TYPE Journal Article YEAR 2011
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Utility-scale grid-tied PV inverter reliability workshop summary report

Atcitty, Stanley A.; Granata, Jennifer E.; Quintana, Michael A.

A key to the long-term success of the photovoltaic (PV) industry is confidence in the reliability of PV systems. Inverters are the most commonly noted cause of PV system incidents triggered in the field. While not all of these incidents are reliability-related or even necessarily failures, they still result in a loss of generated power. With support from the U.S. Department of Energy's Solar Energy Technologies Program, Sandia National Laboratories organized a Utility-Scale Grid-Tied Inverter Reliability Workshop in Albuquerque, New Mexico, January 27-28, 2011. The workshop addressed the reliability of large (100-kilowatt+) grid-tied inverters and the implications when such inverters fail, evaluated inverter codes and standards, and provided discussion about opportunities to enhance inverter reliability. This report summarizes discussions and presentations from the workshop and identifies opportunities for future efforts.

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TYPE SAND Report YEAR 2011
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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
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Stress testing on silicon carbide electronic devices for prognostics and health management

Marinella, Matthew J.; Smith, Mark A.; Atcitty, Stanley A.

Power conversion systems for energy storage and other distributed energy resource applications are among the drivers of the important role that power electronics plays in providing reliable electricity. Wide band gap semiconductors such as silicon carbide (SiC) and gallium nitride (GaN) will help increase the performance and efficiency of power electronic equipment while condition monitoring (CM) and prognostics and health management (PHM) will increase the operational availability of the equipment and thereby make it more cost effective. Voltage and/or temperature stress testing were performed on a number of SiC devices in order to accelerate failure modes and to identify measureable shifts in electrical characteristics which may provide early indication of those failures. Those shifts can be interpreted and modeled to provide prognostic signatures for use in CM and/or PHM. Such experiments will also lead to a deeper understanding of basic device physics and the degradation mechanisms behind failure.

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TYPE SAND Report YEAR 2011
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Power electronics reliability analysis

Smith, Mark A.; Atcitty, Stanley A.

This report provides the DOE and industry with a general process for analyzing power electronics reliability. The analysis can help with understanding the main causes of failures, downtime, and cost and how to reduce them. One approach is to collect field maintenance data and use it directly to calculate reliability metrics related to each cause. Another approach is to model the functional structure of the equipment using a fault tree to derive system reliability from component reliability. Analysis of a fictitious device demonstrates the latter process. Optimization can use the resulting baseline model to decide how to improve reliability and/or lower costs. It is recommended that both electric utilities and equipment manufacturers make provisions to collect and share data in order to lay the groundwork for improving reliability into the future. Reliability analysis helps guide reliability improvements in hardware and software technology including condition monitoring and prognostics and health management.

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TYPE SAND Report YEAR 2009
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Results 201–280 of 280
Results 201–280 of 280