Identification of two trapping mechanisms responsible of the threshold voltage variation in SiO2/4H-SiC MOSFETs

Patrick Fiorenza,Mario Saggio,Filippo Giannazzo,Salvatore Cascino,Fabrizio Roccaforte

doi:10.1063/5.0012399

Abstract

A method based on cyclic gate bias stress followed by a single point drain current measurement is used to probe the interface or near-interface traps in the SiO2/4H-SiC system over the whole 4H-SiC bandgap. The temperature-dependent instability of the threshold voltage in lateral MOSFETs is investigated, and two separated trapping mechanisms were found. The experimental results corroborate the hypothesis that one mechanism is nearly temperature independent and it is correlated with the presence of near-interface oxide traps that are trapped via tunneling from the semiconductor. The second mechanism, having an activation energy of 0.1 eV, has been correlated with the presence of intrinsic defects at the SiO2/4H-SiC interface.

Highlights

S (NIOTs) that extend spatially into the gate oxide from the SiC interface.[4,5,6,7] Usually, the SiO2/4H-SiC interface physics is studied on simple MOS capacitors,[8,9,10] but the full picture on the real impact of the trapping states can be achieved only by studying the real MOSFET device.[11]
A method based on cyclic gate bias stress followed by a single point drain current measurement is used to probe the interface or nearinterface traps in the SiO2/4H-SiC system over the whole 4H-SiC bandgap
We have recently studied the discharge of the near interface oxide traps (NIOTs) in lateral MOSFETs by transient gate-capacitance[5] and gatecurrent[14,15] measurements

Summary

Introduction

S (NIOTs) that extend spatially into the gate oxide from the SiC interface.[4,5,6,7] Usually, the SiO2/4H-SiC interface physics is studied on simple MOS capacitors,[8,9,10] but the full picture on the real impact of the trapping states can be achieved only by studying the real MOSFET device.[11]. A method based on cyclic gate bias stress followed by a single point drain current measurement is used to probe the interface or nearinterface traps in the SiO2/4H-SiC system over the whole 4H-SiC bandgap.

Results

Conclusion