As a very promising epitaxy technology, the remote epitaxy has attracted extensive attention in recent years, in which graphene is the most used interlayer material. As an isomorphic of graphene, two-dimensional (2D) hexagonal boron nitride (h-BN), is another promising interlayer for the remote epitaxy. However, there is a current debate on the feasibility of using h-BN as interlayer in the remote epitaxy. Herein, we demonstrate that the potential field of sapphire can completely penetrate monolayer h-BN, and hence the remote epitaxy of ZrS₂ layers can be realized on sapphire substrates through monolayer h-BN. The field of sapphire can only partially penetrate the bilayer h-BN and result in the mixing of remote epitaxy and van der Waals (vdWs) epitaxy. Due to the weak interfacial scattering and high crystalline quality of ZrS₂ epilayer, the ZrS₂ photodetector with monolayer h-BN shows the best performance, with an on/off ratio of more than 2 × 10⁵ and a responsivity up to 379 mA·W⁻¹. This work provides an efficient approach to prepare single-crystal transition metal dichalcogenides and their heterojunctions with h-BN, which have great potential in developing large-area 2D electronic devices.

Recently, group-IVB semiconducting transition metal dichalcogenides (TMDs) of ZrS₂ have attracted significant research interest due to its layered nature, moderate band gap, and extraordinary physical properties. Most device applications require a deposition of high quality large-area uniform ZrS₂ single crystalline films, which has not yet been achieved. In this work, for the first time, we demonstrate the epitaxial growth of high quality large-area uniform ZrS₂ films on c-plane sapphire substrates by chemical vapor deposition. An atomically sharp interface is observed due to the supercell matching between ZrS₂ and sapphire, and their epitaxial relationship is found to be ZrS₂ (0001)[ $10\overline{1}0$]||Al₂O₃ (0001)[ $11\overline{2}0$]. The epitaxial ZrS₂ film exhibits n-type semiconductor behavior with a room temperature mobility of 2.4 cm²·V⁻¹·s⁻¹, and the optical phonon is the dominant scattering mechanism at room temperature or above. Furthermore, the optoelectronic applications of ZrS₂ films are demonstrated by fabricating photodetector devices. The ZrS₂ photodetectors exhibit the excellent comprehensive performance, such as a light on/off ratio of 10⁶ and a specific detectivity of 2.6 × 10¹² Jones, which are the highest values compared with the photodetectors based on other group-IVB two-dimensional TMDs.