Surface relaxation and oxygen adsorption behavior of different SiC polytypes: a first-principles study

Area of Science:

• Materials Science
• Surface Science
• Computational Chemistry

Background:

• Silicon carbide (SiC) is a crucial semiconductor material with diverse polytypes.
• Understanding surface properties is vital for SiC-based device applications.
• Surface relaxation and adsorption behavior significantly influence material performance.

Purpose of the Study:

• To systematically investigate surface relaxations and oxygen adsorption on various SiC surfaces.
• To elucidate the relationship between surface structure, polytype, and adsorption energy.
• To provide insights into the atomic-level interactions governing oxygen adsorption on SiC.

Main Methods:

• Utilizing density functional theory (DFT) calculations for systematic studies.
• Analyzing electrostatic interactions and spin density distributions for surface relaxation trends.
• Correlating adsorption energies with stacking sequences for different configurations.

Main Results:

• Surface relaxation trends are explained by electrostatic interactions and spin density.
• Oxygen adsorption energies on Si-terminated SiC surfaces correlate with the polytypic translation number T(I).
• Adsorption energies on C-terminated SiC surfaces and on-top configurations on Si-terminated surfaces are primarily dependent on the topmost layer's stacking.

Conclusions:

• The stacking sequence significantly impacts oxygen adsorption on Si-terminated SiC surfaces.
• C-terminated SiC surfaces exhibit adsorption behavior less sensitive to deeper layer stacking.
• These findings offer a fundamental understanding for designing SiC surfaces with tailored properties.