The effect of silicon doping on the growth and properties of similar to 1.0 mu m - thick AlxGa1-xN (0.50 <= x <= 0.55) layers grown on semipolar (11 (2) over bar2) AlN templates by metalorganic vapour phase epitaxy was studied. The layers were grown with different disilane/group-III precursors ratios that varied from 2.8 x 10(-5) to 3.4 x 10(-4). The surface morphology of the Si-doped (11 (2) over bar2) AlGaN layers showed undulations along [1 (1) over bar 00](AlGaN,AlN) with a root-mean square roughness of about 4.0 nm within a scan range of 20 x 20 mu m(2). Different photoluminescence peaks have been linked to negatively charged cation vacancies (V-III(3-)) and their complexes with impurities such as V-III(3-) - 3O(N)(1+), (V-III complex)(1-), and (V-III complex)(2-). The optimised AlGaN:Si layer exhibited a carrier concentration of similar to 1.2 x 10(19) cm(-3), a carrier mobility of 30.7 cm(2)/V s, and a resistivity of 0.018 Omega cm, as determined by Hall-effect measurements at room temperature. A correlation between the resistivity and luminescence emission intensities of AlGaN near-band-edge and impurity-related complexes was found. (C) 2016 Elsevier B.V. All rights reserved.