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Updated: May 31, 2026

Probe Type II Band Alignment in One-Dimensional Van Der Waals Heterostructures Using First-Principles Calculations
Published on: October 12, 2019
The photogalvanic effect in 2D van der Waals heterojunctions M2XT2/SiC via first-principles calculations
Meng Guo1,2, Taifei Zhao1,2, Zhen Cui1,2
1School of Automation and Information Engineering, Xi'an University of Technology, Xi'an, 710048, P.R. China. zcui@xaut.edu.cn.
Abstract:
This first-principles study systematically investigates the structural, electronic, and optoelectronic properties of M2XT2/SiC (M = Sc, Y; X = C; T = F, Cl, Br) van der Waals heterojunctions. The four examined systems (Sc2CBr2/SiC, Sc2CCl2/SiC, SiC/Y2CF2, and SiC/Y2CCl2) retain their monolayer band characteristics while forming stable heterojunctions with indirect bandgaps. The first three configurations clearly show that the VBM and CBM are confined in SiC and M2XT2, respectively, indicating a type-II band alignment. However, for SiC/Y2CF2, both the VBM and CBM are confined in Y2CF2, indicating a type-I band alignment. Notably, SiC/Y2CCl2 demonstrates exceptional electron mobility (6.99 × 103 cm2 V-1 s-1). Charge density difference analysis reveals electron transfer from SiC to MXene layers, facilitated by a built-in electric field that suppresses carrier recombination. All heterojunctions exhibit enhanced light absorption and reduced bandgaps compared to SiC, with SiC/Y2CF2 showing an optimal photoresponse at 3.2 eV photon energy and the highest extinction ratio. These findings highlight the potential of MXene/SiC heterojunctions for tailored optoelectronic applications.
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