Centimeter‐Scale PdS₂ Ultrathin Films with High Mobility and Broadband Photoresponse

Abstract

2D materials with mixed crystal phase will lead to the nonuniformity of performance and go against the practical application. Therefore, it is of great significance to develop a valid method to synthesize 2D materials with typical stoichiometry. Here, 2D palladium sulfides with centimeter scale and uniform stoichiometric ratio are synthesized via controlling the sulfurization temperature of palladium thin films. The relationship between sulfurization temperature and products is investigated in depth. Besides, the high‐quality 2D PdS2 films are synthesized via sulfurization at the temperature of 450–550 °C, which would be compatible with back‐end‐of‐line processes in semiconductor industry with considering of process temperature. The PdS2 films show an n‐type semiconducting behavior with high mobility of 10.4 cm2 V−1 s−1. The PdS2 photodetector presents a broadband photoresponse from 450 to 1550 nm. These findings provide a reliable way to synthesizing high‐quality and large‐area 2D materials with uniform crystal phase. The result suggests that 2D PdS2 has significant potential in future nanoelectronics and optoelectronic applications.

Controllable growth of wafer-scale PdS and PdS2 nanofilms via chemical vapor deposition combined with an electron beam evaporation technique

“…2(b) presents Raman spectrum of the synthesized PdS 2 NF. Two Raman peaks were observed at 299 cm −1 and 422 cm −1 corresponding to the E g mode and A g mode of PdS 2 , respectively, which are in good agreement with previous reports [13] . Raman mapping of the representative A g mode (422 cm −1 ) is displayed in Fig.…”

Layer-dependent electronic structures and optical properties of two-dimensional PdSSe

“…69 In fact, all the valence electrons of Pd 2+ are localized, which determines the semiconducting nature of the PdX 2 . 66,68,82 Moreover, the same as other TMDCs, 47 the strong coupling between layers in PdX 2 makes the band gap decrease gradually with increasing number of layers. 44,48,60,65 Experimentally, accurate measurement of the band gap of PdX 2 is very challenging.…”

“…All the band gaps of the few-layer PdS 2 , PdSSe and PdSe 2 shows a similar decreasing trend along with the increasing layer number, and decreases dramatically for the bulk phase, which are in good agreement with previous experimental reports. 65,66 The decrease of the band gap can be attributed to the orbital hybridization due to the interlayer coupling caused by the increasing layer number, similar to the MoS 2 and black phosphorus. Furthermore, Pd (10 valence electrons) has more valence electrons than both Mo (6 valence electrons) and P (5 valence electrons), which leads to stronger orbital hybridization in PdSe 2 and PdSSe, 99 resulting in a larger degree of layer-dependent band gap.…”

“…60 PdX 2 also shows a layer-dependent electronic structure, and excellent optical, dielectric and transport properties upon varying the thickness of the PdX 2 flakes from single layer to multilayers. [61][62][63][64][65][66][67] Such extraordinary layer-dependent properties of PdX 2 motivate us to explore the electronic structure and optical properties of the new PdX 2 family compound PdSSe by manipulating the layer number. The 2O phase PdSSe is an isostructural material of the orthorhombic PdS 2 and PdSe 2 , which has been synthesized for over half a century.…”

“…60 PdX 2 also shows a layer-dependent electronic structure, and excellent optical, dielectric and transport properties upon varying the thickness of the PdX 2 flakes from single layer to multilayers. 61–67…”