Synthesis of Mo1−xNbxS2 thin films by separate-flow chemical vapor deposition with chloride sources

Abstract

The doping of element (Nb, Ta, etc.) into MoS 2 , one of the layered transition metal dichalcogenides, is a key technology for electronic devices because the lack of the p-type MoS 2 has limited the range of applications. We report that the Mo 1-x Nb x S 2 thin films were synthesized on SiO 2 /Si substrates by chemical vapor deposition (CVD). It was critical to use chloride sources (MoCl 5 and NbCl 5) for the synthesis of Mo 1-x Nb x S 2. The Nb concentration can be increased to 10% by controlling the supplied amount of Nb using a separate-flow CVD apparatus. The Raman spectra changed as the Nb concentration increased, appearing E 2 (Nb-S) vibrational mode. The photoluminescence (PL) at 655 nm, 2 attributed to emission from excitons, disappeared, when Nb was incorporated into the MoS 2. PL due to trions at 680 nm was observed for the Mo 1-x Nb x S 2 thin films.

Growth of Highly Oriented (VNbMoTaW)S2 Layers

“…Transition-metal dichalcogenides (TMDCs) such as MoS 2 and WS 2 are well-known as petrochemical catalysts and as dry lubricants. , Atomically thin crystalline sheets of TMDCs have attracted attention for applications in electronics, valleytronics, and more . Probably, the most attractive aspect of TMDCs as two-dimensional (2D) layered materials is the fact that their cation and anion compositions and hence their functionalities can be controlled. − Experimental investigations of TMDC alloys have however largely been limited to two-cation/anion systems with a few exceptions. − The concept of entropy-stabilized alloys, now extended to a variety of compounds (borides, carbides, nitrides, , oxides, and quasi-2D MXenes , ), is applicable to TMDCs. Among the TMDCs, alloys with five transition-metals have the highest entropy of mixing (−1.6 RT , where R is the universal gas constant), thereby suggesting an entropically stabilized configuration; density functional theory (DFT) calculations , coupled with experiments of selected group 5 and 6 cation compositions revealed that although some of the ternary alloys are unstable, high-entropy alloy (HEA) TMDCs are stable with superior thermal, electrochemical, and electronic characteristics.…”