The Impact of Interfacial Charge Trapping on the Reproducibility of Measurements of Silicon Carbide MOSFET Device Parameters

Abstract

Silicon carbide is an emerging material in the field of wide band gap semiconductor devices. Due to its high critical breakdown field and high thermal conductance, silicon carbide MOSFET devices are predestined for high-power applications. The concentration of defects with short capture and emission time constants is higher than in silicon technologies by orders of magnitude which introduces threshold voltage dynamics in the volt regime even on very short time scales. Measurements are heavily affected by timing of readouts and the applied gate voltage before and during the measurement. As a consequence, device parameter determination is not as reproducible as in the case of silicon technologies. Consequent challenges for engineers and researchers to measure device parameters have to be evaluated. In this study, we show how the threshold voltage of planar and trench silicon carbide MOSFET devices of several manufacturers react on short gate pulses of different lengths and voltages and how they influence the outcome of application-relevant pulsed current-voltage characteristics. Measurements are performed via a feedback loop allowing in-situ tracking of the threshold voltage with a measurement delay time of only 1 μs. Device preconditioning, recently suggested to enable reproducible BTI measurements, is investigated in the context of device parameter determination by varying the voltage and the length of the preconditioning pulse.

Keywords

• hysteresis
• device parameters
• reproducibility
• device characteristics
• silicon carbide
• threshold voltage