Optical Emission Correlated to Bias Temperature Instability in SiC MOSFETs

Feil, Maximilian W.; Reisinger, H.; Kabakow, André; Aichinger, Thomas; Gustin, Wolfgang

doi:10.1109/irps48227.2022.9764584

Cited by 9 publications

(14 citation statements)

References 21 publications

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“…A monoexponential decay of the SiPM current indicates that most photons are emitted simultaneously, as a monoexponential decay is the intrinsic recovery behavior of a SiPM cell. Light emission at a gate voltage transient is therefore a fast process happening at the gate voltage edge 40 . The first hint of a relationship between the photon emission and hysteresis can be found by comparing the photon emission in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Others have also performed optical experiments based on laser excitation [30][31][32][33][34][35][36] . In contrast to these well-known approaches, there have been only a few indications that switching a SiC MOSFET electrically from accumulation to inversion or vice versa can lead to light emission via a radiative recombination process [37][38][39][40] . By detecting photons through the polysilicon and the SiO 2 gate dielectric of dedicated test structures, field-effect stimulated radiative recombination was observed in the SiC bulk and via defects at the SiC/SiO 2 interface, whereby the focus was mainly on time-gating the spectral detection and spatially resolving the spread of the recombining charges.…”

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confidence: 99%

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Electrically stimulated optical spectroscopy of interface defects in wide-bandgap field-effect transistors

et al. 2023

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Wide-bandgap semiconductors such as silicon carbide, gallium nitride, and diamond are inherently suitable for high power electronics for example in renewable energy applications and electric vehicles. Despite the high interest, the theoretical limit regarding device performance has not yet been reached for these materials. This is often due to charge trapping in defects at the semiconductor-insulator interface. Here we report a one-to-one correlation between electrically stimulated photon emission and the threshold voltage shift obtained from a fully processed commercial 4H-SiC metal-oxide-semiconductor field-effect power transistor. Based on this observation, we demonstrate that the emission spectrum contains valuable information on the energetic position of the charge transition levels of the responsible interface defects. We etch back the transistor from the reverse side in order to obtain optical access to the interface and record the emitted light. Our method opens up point defect characterization in fully processed transistors after device passivation and processing. This will lead to better understanding and improved processes and techniques, which will ultimately push the performance of these devices closer to the theoretical limit.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Electrically stimulated optical spectroscopy of interface defects in wide-bandgap field-effect transistors

et al. 2023

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“…One key finding of previous studies was that at any given gate switching and temperature conditions, the resultant Vth drift depends exclusively on the number of switching events [1,3,5,11]. The total stress time as well as the duty cycle is only of minor or even no importance [3,4].…”

Section: Assessment and Illustration Of Worst-case Driftmentioning

confidence: 99%

“…These defects are predominantly recombination centers at the SiC/SiO2 interface that promote the transition of large numbers of conduction band electrons into the valance band in every single switching cycle. We recently discovered that a small fraction of these recombination events is radiative [8]. Emitted photons from the SiC/SiO2 interface can be detected at the reverse side of fully processed chips after etching away parts of the backside metallization.…”

Section: Introductionmentioning

confidence: 99%

“…Emitted photons from the SiC/SiO2 interface can be detected at the reverse side of fully processed chips after etching away parts of the backside metallization. Their spectrum is virtually a fingerprint of the interface and the peaks in the spectrum can be correlated to the density functional theory (DFT) simulations to reveal the microphysical structure of the point defects [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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Assessing, Controlling and Understanding Parameter Variations of SiC Power MOSFETs in Switching Operation

Aichinger

Feil

Salmen

2023

KEM

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Semiconductor manufacturers and researchers have recently revealed that under specific bipolar gate switching conditions SiC MOSFETs exhibit parameter drift dynamics different from those typically observed in static qualification stress tests. In response to this finding, we present an approach for assessing the worst-case drift of data-sheet-relevant electrical parameters in a simple and transparent manner for a large variety of application profiles. We also introduce an empirical model that may explain the drift dynamics observed under gate switching stress; and discuss a recently developed interface characterization technique that has the potential to reveal the nature of point defects at the SiC/SiO2 interface presumably related to the gate switching instability in SiC MOSFETs.

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Temperature-dependent electroluminescence of a gate pulsed silicon carbide metal–oxide–semiconductor field-effect transistor: Insight into interface traps

Weger¹,

Feil

Orden³

et al. 2023

Journal of Applied Physics

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Switching a silicon carbide (SiC) metal–oxide–semiconductor field-effect transistor between inversion and accumulation with removed drain and grounded source terminals leads to defect-assisted carrier recombination and light emission. The energy spectrum of the emitted photons provides valuable information on the involved defects, located both at the 4H-SiC/SiO2 interface and in the 4H-SiC bulk. Here, we measured and analyzed the emitted light over a broad temperature range between 12 and 297 K. Our results reveal two local maxima in light intensity around 30 and 140 K. Most importantly, the local intensity maxima and the related temperatures correlate with both the overall recombination current and gate capacitance measurements. The spectral analysis allowed us to distinguish between recombinations occurring on 4H-SiC bulk defects and 4H-SiC/SiO2 interface-related defects. We explain an initial increase of light emission with decreasing temperature to competing non-radiative pathways with activation energies of 34 and 60 meV for SiC/SiO2 interface- and 4H-SiC bulk-related emissions, respectively. Based on an extensive literature review, we link the measured photon emission to donor–acceptor pair recombination, the EH6/7 or the Z1/2 defect centers. In addition to that, we could link a prominent peak at 2.915 eV to the L1 line of the D1-center. Most importantly, we conducted our own ab initio simulations revealing that recombination via PbC-centers, previously identified with carbon dangling bonds at the 4H-SiC/SiO2 interface [Cottom et al., J. Appl. Phys. 124, 045302 (2018)], could also provide an explanation for the photon emission around 1.75 eV. Finally, our simulation of an interface-related silicon vacancy VSi,I reveals a radiative transition around 2.8 eV.

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Optical Emission Correlated to Bias Temperature Instability in SiC MOSFETs

Cited by 9 publications

References 21 publications

Electrically stimulated optical spectroscopy of interface defects in wide-bandgap field-effect transistors

Electrically stimulated optical spectroscopy of interface defects in wide-bandgap field-effect transistors

Assessing, Controlling and Understanding Parameter Variations of SiC Power MOSFETs in Switching Operation

Temperature-dependent electroluminescence of a gate pulsed silicon carbide metal–oxide–semiconductor field-effect transistor: Insight into interface traps

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