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| VOLUME 106 (2017) | ISSUE 1 | PAGE 51 |
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Band gap tuning of Ge/SiC bilayers under an electric field: a density functional study
M. Luo+, Y. E. Xu*, Y. X. Song×
+Department of Physics, Shanghai Second Polytechnic University, 201209 Shanghai, China *Department of Electronic Engineering, Shang Hai Jian Qiao University, 201306 Shanghai, China ×Key Laboratory of Polar Materials and Devices, East China Normal University, 200241 Shanghai, China
Abstract
The structure and electronic properties of Ge/SiC van der Waals (vdW) bilayer under the influence of an electric field have been investigated by the first-principles method. Without an electric field, the system shows a small band gap of 126 meV at the equilibrium state. Interestingly, by applying a vertical external electric field, the results present a parabola-like relationship between the band gap and the strength. As the negative E-field changes from 0.0 to -0.40 V/Å, the band gap first increases to a maximum of about 378 meV and then decreases to zero. A similar trend is exhibited for the positive E-field, ranging from 0.0 to +0.40 V/Å. The band gap reaches a maximum of about 315 meV at +0.10 V/Å. The significant variations of band gap are owing to different states of Ge, Si, and C atoms in conduction band and valence band. The predicted electric field tunable band gap of the Ge/SiC vdW heterostructures is very promising for its potential use in nanodevices. |