Selective phase growth and precise-layer control in MoTe2
James P. Fraser, Liudvika Masaityte, Jingyi Zhang, Stacey Laing, Juan Carlos Moreno‐López, Adam F. McKenzie, Jessica C. McGlynn, Vishal Panchal, Duncan Graham, Olga Kazakova, Thomas Pichler, Donald A. MacLaren, David A. J. Moran, Alexey Y. Ganin
Abstract
Abstract Minor structural changes in transition metal dichalcogenides can have dramatic effects on their electronic properties. This makes the quest for key parameters that enable a selective choice between the competing metallic and semiconducting phases in the 2D MoTe 2 system compelling. Herein, we report the optimal conditions at which the choice of the initial seed layer dictates the type of crystal structure of atomically-thin MoTe 2 films grown by chemical vapour deposition (CVD). When Mo metal is used as a seed layer, semiconducting 2H-MoTe 2 is the only product. Conversely, MoO 3 leads to the preferential growth of metallic 1T′-MoTe 2 . The control over phase growth allows for simultaneous deposition of both 2H-MoTe 2 and 1T′-MoTe 2 phases on a single substrate during one CVD reaction. Furthermore, Rhodamine 6G dye can be detected using few-layered 1T′-MoTe 2 films down to 5 nM concentration, demonstrating surface enhanced Raman spectroscopy (SERS) with sensitivity several orders of magnitude higher than for bulk 1T′-MoTe 2 .