Method and arrangement for forming a transition metal dichalcogenide layer

A method of forming a transition metal dichalcogenide layer on a substrate, the method comprising:

• disposing, in a chamber having a closed end and an opening opposite to the closed end, a transition metal oxide at the closed end, and a non-gaseous chalcogen scavenger at the opening and in proximity to the transition metal oxide, wherein the non-gaseous chalcogen scavenger is 10 cm or less away from the transition metal oxide;
• placing a chalcogen source in a heating zone with the closed end as a physical barrier disposed between the transition metal oxide and the chalcogen source;
• disposing the substrate downstream of the transition metal oxide and the chalcogen source;
• generating vapors of the transition metal oxide and vapors of the chalcogen source, wherein the non-gaseous chalcogen scavenger reacts preferentially with the vapors of the chalcogen source;
• directing an inert gas from an inert gas source (i) toward the heating zone with the chalcogen source in a path the inert gas flows and (ii) at the vapors generated from the transition metal oxide and the chalcogen source toward the substrate, with the inert gas prevented from directly contacting the transition metal oxide and the non-gaseous chalcogen scavenger by the closed end, so as to dispose the vapors generated from the transition metal oxide and the chalcogen source on the substrate;
• and
• reacting the vapors of the transition metal oxide and the chalcogen source on the substrate to obtain the transition metal dichalcogenide layer on the substrate.