First-Principles Study on Electronic Structure and Optical Properties of Be2C/WSi2N4 Heterostructure

doi:10.16553/j.cnki.issn1000-985x.2026.0045

Abstract

Abstract: In order to reveal the microscopic interface mechanism of Be₂C/WSi₂N₄ heterostructure and its response to external strain， and further to provide theoretical support for the design of novel tunable optoelectronic devices， this paper systematically investigated the electronic structure， optical properties and biaxial strain modulation effects of Be₂C/WSi₂N₄ heterostructure by employing first-principles calculations based on density functional theory. The results indicate that compared with monolayer materials， the Be₂C/WSi₂N₄ heterostructure exhibits a typical type-Ⅱ band alignment， and a built-in electric field pointing from Be₂C to WSi₂N₄ is formed at the interface， which effectively promotes the spatial separation of photogenerated carriers. The calculated results of optical properties demonstrate that the heterostructure possesses a remarkably enhanced light absorption capacity in contrast with monolayer materials， and its maximum absorption coefficient reaches 22.0×10⁵ cm^-1. Within the biaxial strain range from -4% to +4%， the tensile strain reduces the band gap and induces a red shift of the absorption spectrum， while the compressive strain increases the band gap and leads to a blue shift of the absorption spectrum. In addition， the strain exerts a prominent effect on the transition of band gap types. This research offers a theoretical basis for the application of two-dimensional heterostructures represented by Be₂C/WSi₂N₄ in tunable optoelectronic devices.

Key words: Be₂C/WSi₂N₄; heterostructure; first-principle; electronic structure; optical property; strain modulation

CLC Number:

O469

TU Minrui, XIE Quan, YANG Qian, HUANG Sili, YU Gangyuan, LIN Bikang. First-Principles Study on Electronic Structure and Optical Properties of Be₂C/WSi₂N₄ Heterostructure[J]. Journal of Synthetic Crystals, 2026, 55(8): 1297-1305.

Figures/Tables 9

Fig.1 Structure top and side views of Be2C and WSi2N4. （a） Monolayer Be2C；（b） monolayer WSi2N4

Fig.2 Be2C/WSi2N4 heterostructure models with different stacking methods

Table 1 Lattice constants （a， b）， interlayer distance （d） and binding energy （Eb） for six stacking models of Be2C/WSi2N4 heterostructure

Model	a（=b）/Å	d/Å	E_b/（meV·Å^-2）
A	5.84	2.751	-6.225
B	5.84	2.763	-5.673
C	5.84	2.029	-4.263
D	5.86	1.873	-3.485
E	5.86	1.880	-5.198
F	5.86	1.884	-5.062

Fig.3 Band structures of heterostructure. （a） Be2C；（b） WSi2N4；（c） Be2C/WSi2N4

Fig.4 Phonon dispersion spectra of Be2C/WSi2N4 heterostructure （a） and energy and temperature fluctuation curves obtained from AIMD simulation of Be2C/WSi2N4 heterostructure at 300 K for 12 ps （b）

Fig.5 Electronic structure properties of Be2C/WSi2N4 heterostructure. （a） Projected band structure；（b） partial density of states and total density of states；（c） planar-averaged electrostatic potential；（d） planar-averaged charge density difference

Fig.6 Optical absorption coefficient of Be2C/WSi2N4 heterostructure as a function of photon energy

Fig.7 Band structures of Be2C/WSi2N4 heterostructure under biaxial strain ranging from -4% to +4%

Fig.8 Absorption spectra of Be2C/WSi2N4 heterostructure under biaxial strain ranging from -4% to +4%

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First-Principles Study on Electronic Structure and Optical Properties of Be₂C/WSi₂N₄ Heterostructure

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