First-principles exploration of the electronic versatility of the GeH/SiSb heterostructure through stacking and electric fields

Abstract

Designing heterostructures is crucial for developing advanced materials with tailored properties for specific applications. In this study, we explored the intrinsic properties, stability, and tunability of the GeH/SiSb heterostructure through various stacking patterns and the application of electric fields. Our findings confirm that combining GeH and SiSb monolayers creates a stable heterostructure, as evidenced by phononic spectrum analysis, AIMD simulations, and mechanical property evaluations. Depending on the stacking patterns, the heterostructure exhibits either type-I or type-II band alignments. Additionally, the application of electric fields effectively modulates the band gap, facilitates transitions between type-I and type-II alignments, and transforms the band gap from indirect to direct. These findings underscore the versatility of the GeH/SiSb heterostructure for next-generation optoelectronic devices, offering precise electronic property control to enhance device performance.

Fig. 1. (i) Atomic structures, (ii) band structures, (iii) phonon spectra and (iv) AIMD simulations of the (a) GeH and (b) SiSb monolayers. Blue and orange balls stand for the Ge and H atoms, respectively, while the purple and green balls represent the Si and Sb atoms, respectively.

Fig. 2. The atomic structures of six different stacking configurations of the GeH/SiSb heterostructure, including (a) AA1, (b) AB1, (c) AC1, (d) AA2, (e) AB2 and (f) AC2.

Fig. 3. The visualization of the electron localization function (ELF) in the GeH/SiSb heterostructure for all patterns. Electrons are fully localized when the ELF equals 1.

Fig. 4. (a) The weighted projections of the band structures and (b) band gaps of the GeH/SiSb heterostructure for all patterns. The weighted projections of the GeH and SiSb layers are denoted by red and blue circles, respectively. Green and purple arrows represent the type-I and type-II band alignments of the heterostructure.

Fig. 5. PDOS of all atoms in the GeH/SiSb heterostructure for (a) AA1, (b) AB1, (c) AC1, (d) AA2, (e) AB2 and (f) AC2.

Fig. 6. (a) The phonon spectrum, (b) fluctuations in the total energy and temperature and (c) Young's modulus of the GeH/SiSb heterostructure for the most favorable pattern.

Fig. 7. (a) Electrostatic potential and (b) charge density difference of the GeH/SiSb heterostructure. The 3D isosurface of the GeH/SiSb heterostructure is displayed in the inset, where the accumulation and depletion of charges are visualized by yellow and cyan colors.

Fig. 8. The variations in (a) the band gap of the GeH/SiSb heterostructure and (b) band edges of the GeH and SiSb layers upon the application of electric fields. (c) The planar-average CDD of the GeH/SiSb heterostructure under different strengths of applied electric fields.

Fig. 9. (a) Weighted projections of the band structures of the GeH/SiSb heterostructure under (a) negative and (b) positive electric fields. The weighted projections of the GeH and SiSb layers are denoted by red and blue circles, respectively. Green and purple arrows represent the type-I and type-II band alignments of the heterostructure.