Atomic layer deposition of Zn(O,S) thin films with tunable electrical properties by oxygen annealing

Zinc oxysulfide, Zn(O,S), films grown by atomic layer deposition were annealed in oxygen to adjust the carrier concentration. The electron carrier concentration of Zn(O,S) can be reduced by several orders of magnitude from 1019 to 1015 cm−3 by post-deposition annealing in oxygen at temperatures from 200 °C to 290 °C. In the case of Zn(O,S) with S/Zn = 0.37, despite the considerable change in the electron carrier concentration, the bandgap energy decreased by only ∼0.1 eV, and the crystallinity did not change much after annealing. The oxygen/zinc ratio increased by 0.05 after annealing, but the stoichiometry remained uniform throughout the film.