Enhanced electron transport and optical properties of experimentally synthesized monolayer Si9C15: a comprehensive DFT study for nanoelectronics and photocatalytic applications

Abstract

Two-dimensional silicon-carbide (Si_xC_y) materials stand out for their compatibility with current silicon-based technologies, offering unique advantages in nanoelectronics and photocatalysis. In this study, we employ density functional theory and nonequilibrium Green's function methods to investigate the electronic properties, electron transport characteristics, and optoelectronic qualities of experimentally synthesized monolayer Si₉C₁₅. Utilizing the modified deformation potential theory formula, we unveil Si₉C₁₅'s significant directional anisotropy in electron mobility (706.42 cm² V⁻¹ s⁻¹) compared to holes (432.84 cm² V⁻¹ s⁻¹) in the a direction. The electrical transport calculations reveal that configurations with a 3 nm channel length demonstrate an ON state when biased, reaching a peak current of 150 nA. Moreover, this maximum current value escalates to 200 nA under tensile strain, marking an increase of approximately 100 times compared to the 5 nm channel, which remains in an OFF state. Si₉C₁₅ exhibits high light absorption coefficients (∼10⁵ cm⁻¹) and suitable band edge positions for water splitting at pH 0–7. Applying 1–5% tensile strain can tune the conduction band minimum and valence band maximum closer to the standard redox potentials, enhancing photocatalytic water splitting efficiency. Remarkably, under illumination at pH 0 and 7, Si₉C₁₅ can spontaneously catalyze water splitting, demonstrating its potential as a highly efficient photocatalyst. Our findings emphasize the importance of strain control and device length optimization for performance enhancement in nanoelectronics and renewable energy applications, positioning Si₉C₁₅ as a promising material for high-performance field-effect transistors and photocatalytic water splitting.