@article{bibcite_964,
  author = {Harvey N. Cruzado and John Symon C. Dizon and Gennevieve M. Macam and Rovi Angelo B. Villaos and Thi My Duyen Huynh and Liang-Ying Feng and Zhi-Quan Huang and Chia-Hsiu Hsu and Shin-Ming Huang and Hsin Lin and Feng-Chuan Chuang},
  title = {Band engineering and van Hove singularity on HfX$_{2}$ thin films (X = S, Se, or Te)},
  abstract = {Two-dimensional transition metal dichalcogenides (TMDs) have become well-known due to their versatile and tunable physical properties for potential applications, specifically on low-power and optical devices. Here, we explored the structural stability and electronic properties of bulk and thin-film (from 1 up to 6 layers) structures of hafnium dichalcogenides (HfX$_{2}$, X = S, Se, or Te) using first-principles calculations. Our calculations reveal that the most stable phase is 1T for both thin films and bulk. The bulk and thin-film structures of HfTe$_{2}$ are semimetallic, while those of HfS$_{2}$ and HfSe$_{2}$ are insulating. Both HfS$_{2}$ and HfSe$_{2}$ thin films exhibit a decreasing band gap with increasing thickness, while HfTe$_{2}$ thin films remain semimetallic with increasing number of layers. Moreover, van Hove singularity (vHs), due to the contribution of the pz orbital from S atoms, is observed in 3L-HfS$_{2}$ at the valence band maximum, which can be further enhanced by applying an in-plane biaxial strain, suggesting possible superconductivity. Finally, the bulk and monolayer band structures of HfTe$_{2}$, under HSE06 and GGA + U with the effective Hubbard U parameter of 4.6 eV, are in good agreement with the experimental ARPES data. Our results indeed show that HfX$_{2}$ have sensitive and tunable electronic properties through film thickness control and strain for future potential applications.},
  year = {2021},
  journal = {ACS Appl. Electron. Mater.},
  volume = {3},
  pages = {1071},
  url = {https://doi.org/10.1021/acsaelm.0c00907},
  doi = {10.1021/acsaelm.0c00907},
}