Structure and the emission and piezoelectric properties of MOCVD-grown ZnS, ZnS-ZnO, and ZnO films

Zinc sulfide and zinc oxide films are produced by the pyrolysis of organometallic compounds (MOCVD technique). The objects of investigation are the phase composition, structure, surface topology, and the optical and piezoelectric properties of the films obtained under different process conditions. The composition of the films depends on the purity level of the precursor, substrate temperature (as the temperature grows, the composition varies from ZnS to ZnO), and evaporation rate (with an increase in this rate, the composition changes from ZnO to ZnS). In addition, ZnS turns into ZnO upon annealing at 600°C. In the most perfect ZnS films, which are obtained with the purest precursor, intense edge luminescence (3.64 eV) is observed for the first time at room temperature. Two-phase ZnS-ZnO films obtained from a cheap precursor are characterized by pronounced piezoelectric properties and can be used in designing different piezoelectric and acoustoelectric devices.