Microscopic Mechanism of Carbon Annihilation upon SiC Oxidation due to Phosphorous Treatment: Density-Functional Calculations Combined with Ion Mass Spectrometry

TL;DR

This study combines density-functional calculations and ion mass spectrometry to reveal how phosphorous treatment promotes carbon removal during SiC oxidation by acting as a carbon absorber at the microscopic level.

Contribution

It uncovers the microscopic mechanism of carbon annihilation due to phosphorous treatment in SiC oxidation, supported by both theoretical calculations and experimental measurements.

Findings

Phosphorus in the oxide forms a four-fold coordinated PO unit.

The PO unit attracts and absorbs carbon ejected from the interface.

Experimental carbon profiles support the theoretical mechanism.

Abstract

We report first-principles static and dynamic calculations that clarify the microscopic mechanism of carbon annihilation due to phosphorous treatment upon oxidation of silicon carbide (SiC). We identify the most stable form of the phosphorus (P) in the oxide as the four-fold coordinated with the dangling PO unit and find that the unit attracts carbon ejected from the interface, thus operating as a carbon absorber. This finding provides a microscopic reasoning for the first time for the promotion of the oxidation reaction on one hand and the annihilation of the C-related defects at the interface on the other. Secondary ion mass spectrometry measurements are also performed and the obtained carbon profile corroborates the theoretical finding above.