Modifying electrical and optical properties of monolayer silicon carbide through molecular doping

Li-Sheng Lin^1*, Yu-Chenh Feng², Jui-Cheng Kao², Yu-Chieh Lo², Jyh-Pin Chou¹

¹Graduate School of Advanced Technology, National Taiwan University, Taipei, Taiwan
²Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, Hsinchu, Taiwan

* Presenter:Li-Sheng Lin, email:F11941095@ntu.edu.tw

In recent years, significant progress has been made in developing two-dimensional materials, such as silicon carbide (2D SiC). This material has excellent electronic and thermal characteristics similar to bulk SiC and forms a honeycomb lattice with alternating silicon and carbon atoms. Unlike conventional atomic doping, molecular doping can more easily control the carrier type and quantity in 2D materials without perturbing the geometric and electronic structures. Through first-principles calculations, we found that doping 2D SiC with specific organic molecules — TTF, CCO, CN6-CP, F2HCNQ, F4TCNQ, F6TNAP, TCNE, and TCNQ —can effectively tune its electronic and optical properties. TTF serves as an n-dopant for 2D SiC, while CCO, CN6-CP, F2HCNQ, F4TCNQ, F6TNAP, TCNE, and TCNQ offer p-dopant. Applying an external perpendicular electric field in the z-direction can significantly modulate the energy difference between the molecular state and valance band maximum (VBM), also the amount of charge transfer. The adsorption of CCO, TCNQ, F4TCNQ, and CN6-CP molecules on SiC has shown a significant enhancement absorption coefficient in the visible region, making molecular doping 2D SiC a potential candidate material for optoelectronic application. In conclusion, our study demonstrates that molecular doping is an effective strategy to tailor the electronic and optical properties of 2D SiC, paving the way for advanced technological applications.

Keywords: 2D SiC, molecular doping , charge transfer mechanism, absorption spectrum