Sticking coefficient and Si/C ratio of silicon carbide growth species on reconstructed [formula omitted] surface by ab-initio calculations

Abstract

The production of silicon carbide boule for electronic device fabrication is bedeviled by defects and requires the usage of stable, high symmetry, and high-quality substrate, as a seed, for growth morphology dictation. Aside from this, process parameters such as Si/C ratio, growth temperature, and etching play certain roles in polytype stability and defect control. In this work, we estimated the Si/C ratio in the physical vapor transport process (PVT), by first, modeling and investigating several types of 4H–SiC substrates, including ideal (1x1), buckled (2x1), and (2x1) periodic π-bonded chain structures (both Si-face and C-face), via density functional theory, and found the C-face of the 4H–SiC substrate as the most stable among others. On this substrate, silicon carbide growth species get adsorb, stick, and grow, to form large SiC boule (ingot) in the PVT process. In order to have an idea of the defect concentration in the silicon carbide boule, we calculated the Si/C ratio, by estimating the sticking coefficient of individual growth contributing species (Si(g),SiC2(g),SiC(g),Si2C(g),Si2C2(g),Si4C2(g)(I1) and Si4C2(g)(I2)), coupled with their concentrations. The calculated theoretical sticking coefficients for the growth contributing species at 2186 K are respectively, 0.02882, 0.01226, 0.02113, 0.01271, 0.00807, 0.00335 and 0.00433.