Source/drain contacts connecting 2-d material layer and method for forming the same

A method, comprising:

• forming a 2-D material layer over a substrate, wherein the 2-D material layer comprises transition metal atoms and chalcogen atoms;
• providing a metal-containing precursor over the 2-D material layer to made make redox reaction with the 2-D material layer, wherein portions of the chalcogen atoms are replaced with metal elements of the metal-containing precursor;
• and
• forming a gate structure over the 2-D material layer.

A method, comprising:

• forming a 2-D material layer over a substrate, wherein the 2-D material layer comprises transition metal atoms and chalcogen atoms;
• forming a source/drain contact over a source/drain region of the 2-D material layer;
• and
• performing an annealing process to break covalent bonds between portions of the chalcogen atoms and the transition metal atoms, wherein the portions of the chalcogen atoms are diffused away through the source/drain contact during the annealing process.