TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: The first reaction space is fluidically separated from the second reaction space. The step of contacting the substrate: with the first precursor forms a non-self limiting layer of the first metal layer over the substrate; in the second reaction space with the group V precursor comprises providing a group V precursor and a hydrogen containing species; in the first reaction space with the first precursor forms a layer of a first metal layer having a thickness 1 monolayer (ML); and in the second reaction space with the group V precursor forms a group III-V thin film having a thickness less than 1 ML. The method further comprises: heating the substrate while forming the thin film; contacting the first metal layer with hydrogen-containing species in a third reaction space prior to contacting the substrate in the second reaction space with the group V precursor; and contacting the thin film with hydrogen-containing species in a third reaction space. Preferred Components: The active neutral species of nitrogen comprises nitrogen species having the lowest excited state of molecular nitrogen (A3: Sigma u+). The nitrogen-containing species comprises nitrogen, ammonia, hydrazine or mixture of nitrogen and hydrogen. The second precursor comprises plasma activated species of a group V containing molecule, where the group V precursor comprises plasma activated nitrogen-containing species. The first precursor comprises at least one species comprising gallium (preferred), boron, aluminum or indium. The first precursor comprises a metalorganic species. The thin film is group III metal nitride thin film. The hydrogen-containing species are hydrogen and excited species of hydrogen. The group III-V thin film comprises indium gallium nitride of formula (InxGa(1-x)N).x = 0-1. EXAMPLE - Substrate, heated to a temperature of 700 degrees C, was provided in a first reaction space and contacted with trimethylgallium at a pressure of 0.5 Torr. The first exposure of trimethylgallium was sufficient to form a gallium thin film at coverage of 0.5 monolayer (ML). The substrate, heated to a temperature of 700 degrees C, was rotated to a second reaction space and contacted with excited hydrogen-containing species, including hydrogen radicals and ions, at a pressure of 0.5 Torr. Excited hydrogen containing species are formed by providing plasma power of 500 Watts to hydrogen. The substrate, heated to a temperature of 700 degrees C, was rotated to a third reaction space and contacted with a mixture of nitrogen and hydrogen, at a pressure of 0.5 Torr. Plasma power of 500 Watts was provided to the mixture to generate excited species of nitrogen and hydrogen. The substrate, heated to a temperature of 700 degrees C, was rotated to a fourth reaction space and contacted with excited hydrogen-containing species, including hydrogen radicals and ions, at a pressure of 0.5 Torr. The substrate was rotated to the first reaction space, and the steps are repeated to provide a group III-V thin film having, in total, a thickness of 4000 nm.