Influence of the synthesis conditions on gallium sulfide thin films prepared by modulated flux deposition

Abstract

Gallium sulfide thin films were deposited on soda-lime glass substrates by Modulated Flux Deposition (MFD). Using a low deposition rate (1 Å s−1), 100 nm thick layers were prepared at temperatures ranging from 450 to 150 °C with a variable supply of elemental sulfur. EDX analysis showed that these films approached the MX stoichiometry; they corresponded to sulfur-deficient GaS. By raising the availability of sulfur, the bandgap energy (Eg) was increased from 3.2 to 3.6 eV at 350 °C, while it remained constant (∼3.6 eV) at 150 °C; these high Eg values were mainly attributed to quantum size effects. Therefore, high-transmission GaS thin layers can be prepared at only 150 °C by MFD.