Atomic Layer Deposition (ALD) is used for heteroepitaxial film growth at reaction temperatures ranging from 80-400° C. The substrate and film materials are preferably matched to take advantage of Domain Matched Epitaxy (DME). A laser annealing system is used to thermally anneal deposition layer after deposition by ALD. In preferred embodiments, a silicon substrate is overlaid with an AlN nucleation layer and laser annealed. Thereafter a GaN device layer is applied over the AlN layer by an ALD process and then laser annealed. In a further example embodiment, a transition layer is applied between the GaN device layer and the AlN nucleation layer. The transition layer comprises one or more different transition material layers each comprising a AlxGa1-xN compound wherein the composition of the transition layer is continuously varied from AlN to GaN.