Abstract: Disclosed is a chemical vapour deposition injector 100, comprising a gas injector body 104 having a plurality of holes for directing a first gas from a first gas plenum into respective first gas channels of the gas injector body, each first gas channel extending in a first direction and arranged to branch into separate flow paths; a plurality of discrete first conduits, each first conduit being arranged to connect to a respective one of the discrete flow paths for carrying the first gas to a reaction chamber; a second gas channel for directing a second gas from a second gas plenum into the gas injector body, the second gas channel having a longitudinal axis which extends in a second direction transverse to the first direction; and a plurality of discrete second conduits coupled to the second gas channel and arranged to carry the second gas from the second gas channel to the reactor chamber; wherein at least some of the discrete second conduits are arranged between the discrete first conduits.