Transition metal deposition method

A method of depositing a transition metal on a substrate by a cyclical deposition process, the method comprising:

• providing a substrate in a reaction chamber;
• providing a transition metal precursor to the reaction chamber in a vapor phase;
• and
• providing a reactant to the reaction chamber in a vapor phase to form the transition metal on the substrate;
• wherein:
• the transition metal precursor comprises titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, or molybdenum,
• the reactant comprises a group 14 element, and
• at least 60% of the transition metal is deposited as elemental metal, and
• the reactant has a general formula RaMXb or RcXdM-MRcXd, wherein a is 0-3, b is 4-a, c is 0, 1 or 2, d is 3-c, R is hydrocarbon, M is Ge or Sn, and each X is independently any ligand.