We have developed an improved vapor-phase deposition method and apparatus for the application of films/coatings on substrates. The method provides for the addition of a precise amount of each of the reactants to be consumed in a single reaction step of the coating formation process. In addition to the control over the amount of reactants added to the process chamber, the present invention requires precise control over the total pressure (which is less than atmospheric pressure) in the process chamber, the partial vapor pressure of each vaporous component present in the process chamber, the substrate temperature, and typically the temperature of a major processing surface within said process chamber. Control over this combination of variables determines a number of the characteristics of a film/coating or multi-layered film/coating formed using the method. By varying these process parameters, the roughness and the thickness of the films/coatings produced can be controlled.