Strain-Induced Energy Band Gap Opening in Two-Dimensional Bilayered Silicon Film

• Published in: Journal of electronic materials 2016-10, Vol.45 (10), p.5040-5047
• Main Authors: Ji, Z., Zhou, R., Lew Yan Voon, L. C., Zhuang, Y.
• Format: Article
• Language: English
• Subjects: Band gap; Characterization and Evaluation of Materials; Chemistry and Materials Science; Electronics and Microelectronics; Instrumentation; Materials Science; Multilayered thin films; Optical and Electronic Materials; Silicones; Solid State Physics; Stress-strain curves
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-016-4682-3

This work presents a theoretical study of the structural and electronic properties of bilayered silicon film (BiSF) under in-plane biaxial strain/stress using density functional theory (DFT). Atomic structures of the two-dimensional (2-D) silicon films are optimized by using both the local-density approximation (LDA) and generalized gradient approximation (GGA). In the absence of strain/stress, five buckled hexagonal honeycomb structures of the BiSF with triangular lattice have been obtained as local energy minima, and their structural stability has been verified. These structures present a Dirac-cone shaped energy band diagram with zero energy band gaps. Applying a tensile biaxial strain leads to a reduction of the buckling height. Atomically flat structures with zero buckling height have been observed when the AA-stacking structures are under a critical biaxial strain. Increase of the strain between 10.7% and 15.4% results in a band-gap opening with a maximum energy band gap opening of ∼0.17 eV, obtained when a 14.3% strain is applied. Energy band diagrams, electron transmission efficiency, and the charge transport property are calculated. Additionally, an asymmetric energetically favorable atomic structure of BiSF shows a non-zero band gap in the absence of strain/stress and a maximum band gap of 0.15 eV as a −1.71% compressive strain is applied. Both tensile and compressive strain/stress can lead to a band gap opening in the asymmetric structure.