Direct fabrication of two-dimensional ReS2 on SiO2/Si substrate by a wide-temperature-range atomic layer deposition

摘要

The building of high-quality, especially thickness-controllable ReS2, is the crux of researching it and developing its wider application. In this work, ultrathin (1-5 layers) ReS2 with controllable thickness and improved quality is obtained on SiO2/Si substrates, using wide-temperature-range (WTR) atomic layer deposition (ALD). First, a WTR ALD system for building thin films and in situ annealing is constructed. ReS2 of precise thicknesses can be achieved by regulating the number of ALD cycles, controlling the reaction temperature and plasma treatment. In particular, a method of in situ H2S annealing is used to reduce S defects, which improves the quality of ReS2. After annealing, the atomic ratio of S/Re in ReS2 increases from 1.74 to 1.92, considering the presence of Re-O bond at the SiO2-ReS2 interface, which indicates that the S defects in ReS2 films are completely eliminated at annealing temperature of 850 degrees C and 900 degrees C. In particular, at an annealing temperature of 900 degrees C, ReS2 recrystallizes to form about 120 nm triangular grains, and its frictional force is reduced by 27.5% compared with the as-grown ReS2.