Presentation Information
[3C02]Electronic states and optical properties of two-dimensionalgroup IV materials
*Ranferi Cancino Betancourt1,2, Daisuke Nakagawa1, Akira Sumiyoshi1, Shota Sato1, Miguel Cruz Irisson2, Jun Nakamura1 (1. The University of Electro-Communications, 2. Escuela Superior de Ingeniería Mecánica y Eléctrica Unidad Culhuacan)
Graphane, a two-dimensional carbon material with sp³ bonds, was recently synthesized by hydrogenating graphene. Although it is a direct transition semiconductor, the graphane does not absorb light at its bandgap energy. In contrast, planar polysilane its silicon analog, allowed optical transitions. Using first-principles calculations based on density functional theory (DFT), this study compared the optical properties of these Group IV 2D materials. The analysis of optical transition matrix elements (OTM) showed that graphane has nearly zero transition probability at the band edge, while polysilane exhibits finite values, indicating allowed transitions based on the Laporte rule. Wavefunction analysis further explained this behavior. Additionally, excitonic effects were investigated, revealing absorption peaks below the bandgap in both materials due to exciton binding energy, confirming the importance of electron-hole interactions in their optical responses.