Identification of the major cause of endemically poor mobilities in SiC/SiO2 structures

TL;DR

This paper identifies carbon di-interstitial defects generated during thermal oxidation as the primary cause of poor carrier mobilities in SiC/SiO2 structures, explaining persistent low mobilities despite defect passivation efforts.

Contribution

It reveals that thermal oxidation creates specific defects inside SiC substrates, which are the main factor limiting mobility in these structures.

Findings

Thermal oxidation produces carbon di-interstitial defects in SiC.

These defects significantly degrade carrier mobility.

Addressing these defects could improve device performance.

Abstract

Materials with good carrier mobilities are desired for device applications, but in real devices the mobilities are usually limited by the presence of interfaces and contacts. Mobility degradation at semiconductor-dielectric interfaces is generally attributed to defects at the interface or inside the dielectric, as is the case in Si/SiO2 structures, where processing does not introduce detrimental defects in the semiconductor. In the case of SiC/SiO2 structures, a decade of research focused on reducing or passivating interface and oxide defects, but the low mobilities have persisted. By invoking theoretical results and available experimental evidence, we show that thermal oxidation generates carbon di-interstitial defects inside the semiconductor substrate and that they are a major cause of the poor mobility in SiC/SiO2 structures.