Synthesis of indium oxi-sulfide films by atomic layer deposition: The essential role of plasma enhancement

This paper describes the atomic layer deposition of In(2)(S,O)(3) films by using In(acac)(3) (acac = acetylacetonate), H(2)S and either H(2)O or O(2) plasma as oxygen sources. First, the growth of pure In(2)S(3) films was studied in order to better understand the influence of the oxygen pulses. X-Ray diffraction measurements, optical analysis and energy dispersive X-ray spectroscopy were performed to characterize the samples. When H(2)O was used as the oxygen source, the films have structural and optical properties, and the atomic composition of pure In(2)S(3). No pure In(2)O(3) films could be grown by using H(2)O or O(2) plasma. However, In(2)(S,O)(3) films could be successfully grown by using O(2) plasma as oxygen source at a deposition temperature of T = 160 °C, because of an exchange reaction between S and O atoms. By adjusting the number of In(2)O(3) growth cycles in relation to the number of In(2)S(3) growth cycles, the optical band gap of the resulting thin films could be tuned.