Mechanical transfer of electrochemically grown molybdenum sulfide layers to silicon wafer

Abstract

Large area MoS2 ultra-thin film deposition is one of the big challenges in the recent years. Electrodeposition provides an opportunity to grow such ultra-thin films on large scale. However, the transfer of the electrochemically grown film is challenging. Standard transfer of those thin films is done by wet etching in which the underlying substrate is etched. In this work, the polymer coated electrodeposited MoS2 films on Au are separated mechanically from the underlying substrate by using ultra-sonication. Collapse of micron-sized bubbles produced by ultra-sonication at the interface of Au and silicon substrate provides enough energy for separation due to their weak adhesion. The Au layer is then removed by standard Au-etchant (K/KI) and the polymer coated film is transferred to a desired substrate. Ammonium tetrathiomolybdate (ATTM) has been used as precursor material for the electrodeposition of the films. Initial electrochemically grown films consist of MoS3 which is reduced to MoS2 by a post-annealing step at 450–900 °C. Obtained films are investigated by AFM, Raman, UV–Vis and XPS. Crystal quality improves by increasing the post-annealing temperature. The thickness of the thinnest film was found to be equivalent to 2 monolayers of MoS2, which is desirable for future electronics.Graphic abstract