We report the metalorganic vapour phase epitaxy (MOVPE) of CdTe layers on detector-grade travelling heater method (THM)-grown (111)B-CdTe substrates, a technological step towards the fabrication of homoepitaxial p–i–n diodes as nuclear radiation detectors. CdTe layers were grown at 330 °C using dimethylcadmium (Me2Cd) and di-isopropyltelluride. A quantitative analysis of the substrate X-ray surface reflectivity after a sequence of treatment steps, i.e. (i) Br2–methanol etching, (ii) in situ H2 heat cleaning at 350 °C, and (iii) H2 heat cleaning and annealing in H2+Me2Cd atmosphere, demonstrated that the rms roughness of the (111)B surface steadily decreases after each treatment, the smoothest surface being obtained after annealing in H2+Me2Cd. The growth of (111)-oriented homoepitaxial layers depends critically on a combination of in situ substrate treatment and precursor stoichiometry during …