Phase stability of MoTe₂ obtained by tellurization of sputtered molybdenum oxide: The influence of the thickness and the precursor crystallinity

1T′ and 2H MoTe₂ films were obtained by using isothermal close space tellurization of sputtered MoO_x films onto amorphous fused silica or (100) oriented silicon substrates. The influence of the thickness and the crystalline state of the precursor thin films in the obtained phase was analyzed. With this aim, precursors films were sputtered with thicknesses ranging from 5 to 40 nm. From each thickness, one sample was annealed in the air before the tellurization process, and the other was tellurized as sputtered. Misoriented and preferentially oriented crystals were found in all samples, according to grazing incidence and θ–2θ X-rays diffraction measurements, respectively. For samples prepared onto fused silica substrates, 1T′ phase was favored for misoriented crystals except for the samples of the highest thickness tellurized with the annealed thin films precursor. In the case of oriented crystals, they presented a rather different behavior with samples tellurized from annealed precursors preferring the 2H phase. Some experiments performed using crystalline silicon substrates seem to indicate an important influence on the used substrate in the obtained phase. The control of the obtained MoTe₂ phase is a relevant subject due to the potential emerging applications of both 1T′ and 2H crystalline modifications in the context of topological superconductivity, fault-tolerant topological quantum computation, for example.