A method for preparing polycrystalline or single-crystal zinc oxide ZnO on a seed placed in an enclosure under a controlled atmosphere, by sublimation of a zinc oxide source placed in a crucible inside the enclosure and distant from the seed, by formation of gas species, transport of gas species, condensation of gas species on the seed, recombination of the ZnO at the surface of the seed, growth of polycrystalline or single-crystal ZnO on the seed, and cooling of the polycrystalline or single-crystal ZnO, wherein: the zinc oxide source is heated by induction at a temperature, a so-called sublimation temperature, from 900 to 1,400° C. under a pressure from 2.10−3 atmospheres to 0.9 atmospheres; CO is generated in situ as a sublimation activator by supplying at least one oxidizing species, or a mixture of an oxidizing species and of at least one inert gas on a solid carbon source placed inside the enclosure; and control of the stoichiometry of the ZnO is achieved by providing a localized supply with controlled flow rate, for example in an amount from 1 SCCM to 100 SCCM, of at least one oxidizing species or of a mixture of at least one oxidizing species and of at least one inert gas, in the vicinity of a growth interface of the ZnO. A device for carrying out the method.