## 4 Conclusions  
In summary, we have realized the MBE growth of SnSe\({}_{2}\) films on \(\sqrt{3}\)-Sn passivated Si(111) substrate. The analysis of RHEED patterns demonstrates the successful growth and the same in-plane lattice orientation of the grown SnSe\({}_{2}\) with Si(111) substrate, whereas the Sn buffer layer conducts a \(\left(\sqrt{3}\times\sqrt{3}\right)\) reconstruction with in-plane rotation by 30\({}^{\circ}\) relative to both Si(111) and SnSe\({}_{2}\). In addition, the layer-by-layer growth mode of SnSe\({}_{2}\) identified by STM indicates the relatively stronger adsorption effect of \(\sqrt{3}\)-Sn/Si(111) on SnSe\({}_{2}\) adsorbates than the commonly used graphene substrate. Subsequently, from the XPS measurements, we observed the interfacial charge transfer from substrate to SnSe\({}_{2}\), which was further confirmed in the ARPES measurements. Moreover, a new valence band \(\alpha\) located above the original VBM of bulk SnSe\({}_{2}\) emerges in the ML and FL SnSe\({}_{2}\) films, which disappears in the Multi-L SnSe\({}_{2}\) film. We attribute it to the partial T\(\rightarrow\)H structural phase transition of thin SnSe\({}_{2}\) films grown on \(\sqrt{3}\)-Sn/Si(111) substrate, probably driven by the interfacial strain. The direct characterizations of electronic structures of SnSe\({}_{2}\) films, as well as the layer-dependent structural transition, along with the effective band modulation provide significant and important information for the further applications of SnSe\({}_{2}\) films in 2D electronic devices, such as optoelectronics and phase change memory.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app15116150/s1](https://www.mdpi.com/article/10.3390/app15116150/s1)]([https://www.mdpi.com/article/10.3390/app15116150/s1](https://www.mdpi.com/article/10.3390/app15116150/s1)), Section SA. Method for calculating lattice constants from RHEED patterns; Section SB. Full XPS spectra; Section SC. EDCs fitting for determining the CBMs; Section SD. Second-derivative ARPES spectra.  
Conceptualization, Y.Z.; methodology, Z.L., Q.T., K.W., Y.M., Z.F., X.Q., Q.M., C.W. and Y.Z.; software, Y.Z.; validation, Z.L., Q.T., K.W., Y.M. and Y.Z.; formal analysis, Z.L., Q.T., K.W., Y.M. and Y.Z.; investigation, Z.L. and Q.T.; resources, Y.Z.; data curation, Z.L., Q.T., K.W., Y.M. and Y.Z.; writing--original draft preparation, Z.L.; writing--review and editing, Y.Z.; visualization, Z.L., Q.T., K.W. and Y.M.; supervision, C.W. and Y.Z.; project administration, Y.Z.; funding acquisition, Y.Z. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Natural Science Foundation of China (No. 92165205), the Fundamental Research Funds for the Central University (No. 0204/14380228), the Fundamental Research Program of Natural Science Foundation of Jiangsu Province (BK20243011), and the Natural Science Foundation of Hunan Province of China (No. 2024 jj6009).  
Not applicable.  
The raw data supporting the conclusions of this article will be made available by the authors on request.  
The authors declare no conflicts of interest.