AlxGa1-xN/GaN heterostructures (0 <= x <= 1) were deposited on (0 0 01)-sapphire by low-pressure (20 Tort) organometallic vapor phase epitaxy utilizing a range of group-III precursor and NH3 flow rates and a deposition temperature of 1050 degrees C. The Al-mole fraction of AlxGa1-xN layers was controlled by variations in the molar flows of triethylgallium (f(TEG)) and trimethylaluminum (f(TMA)). Characterization by X-ray diffraction confirmed that increasing the f(TMA)/f(TEG) ratio during deposition resulted in increased Al-mole fraction of AlxGa1-xN layers. A linear relationship between the experimental Al-mole fraction of AlxGa1-xN layers and the group-III precursor flows was obtained if a correction factor gamma was introduced such that x = gamma f(TMA)/(gamma f(TMA)+f(TEG)). This correction factor was found to be independent of group-III precursor flows but dependent on NH3 partial pressure. The value of gamma for these experiments decreased from 1.4 to 1.0 when the NH3 partial pressure was increased from 0.8 to 16.0Torr during AlxGa1-xN deposition. The growth rate of AlxGa1-xN layers was found to be a linear combination of the independent AlN and GaN growth rates when equivalent f(TMA) and f(TEG) were utilized under the same deposition conditions. (C) 2010 Published by Elsevier B.V.