Modeling of Phototransistors Based on Quasi-Two-Dimensional Transition Metal Dichalcogenides

This study introduces a comprehensive physical modeling framework for phototransistors based on quasi-two-dimensional (quasi-2D) transition metal dichalcogenides (TMDC), with a particular emphasis on MoS2. By integrating electromagnetic simulations of optical absorption with semiconductor transport calculations, the model captures both dark and photocurrent behaviors across diverse operating conditions. The results accurately reproduce spectral absorption peaks in MoS2 films of varying thicknesses and demonstrate strong agreement with experimental dark current transfer characteristics. A key insight from the study is the critical role of defect states, including traps, impurities, and interfacial imperfections, in governing dark current and photocurrent under channel pinch off conditions. The model successfully replicates the qualitative trends observed in experimental devices, highlighting how small variations in film thickness, doping levels, and contact geometries can significantly influence device performance, in agreement with published experimental data. These findings underscore the importance of precise defect characterization and the optimization of material and structural parameters in phototransistors based on 2D materials. The proposed modeling framework serves as a powerful tool for the design and optimization of next-generation phototransistors, facilitating the integration of 2D materials into practical electronic and optoelectronic applications.