Chemically driven isothermal closed space vapor transport of MoO2: thin films, flakes and in situ tellurization

A novel procedure, based on a closed space vapor transport (CSVT) configuration, has been devised to grow films or flakes of pure MoO2 in a reductive atmosphere, at a relatively low temperature and using MoO3 as the source. In contrast to the conventional CSVT technique, in the proposed method a temperature gradient is not required for the growth to take place, which occurs through an intermediate volatile transport species that is produced in the complex reduction reaction of MoO3. An added value of this simple method is the possibility of transforming the MoO2 into MoTe2, one of the most interesting members of the transition metal dichalcogenide family. This is achieved in a sequential process that includes the growth of Mo oxide and its (in situ) tellurization in two consecutive steps.