Due to the predicted excellent electronic properties superior to group VIB (Mo and W) transition metal dichalcogenides (TMDs), group IVB TMDs have enormous potential in nanoelectronics. Here, the synthesis of ultrathin HfS2 flakes via space-confined chemical vapor deposition, realized by an inner quartz tube, is demonstrated. Moreover, the effect of key growth parameters including the dimensions of confined space and deposition temperature on the growth behavior of products is systematically studied. Typical as-synthesized HfS2 is a hexagonal-like flake with a smallest thickness of ≈1.2 nm (bilayer) and an edge size of ≈5 µm. The photodetector based on as-synthesized HfS2 flakes demonstrates excellent optoelectronic performance with a fast photoresponse time (55 ms), which is attributed to the high-quality crystal structure obtained at a high deposition temperature and the ultraclean interface between HfS2 and the mica substrate. With such properties HfS2 holds great potential for optoelectronics applications. High-quality ultrathin HfS2 flakes are synthesized for the first time via an improved chemical vapor deposition method introducing a confined space, which is employed to construct a precursor growth environment that is stable and precisely tunable regarding reactant concentrations. The photodetector based on the HfS2 flake shows a fast response time of 55 ms.
Published in: "Advanced Functional Materials".