Atomic Layer Deposition of an Sb₂Se₃ Photoabsorber Layer Using Selenium Dimethyldithiocarbamate as a New Se Precursor

Atomic layer deposition (ALD) of antimony selenide (Sb2Se3) is demonstrated using selenium dimethyldithiocarbamate as a new chalcogen precursor with tris(dimethylamino) antimony as a metal source at 150 °C. The ALD chemistry with this organic-selenide precursor is explored as an alternative to highly toxic H2Se. The mechanistic facets of the reactions facilitating the deposition are revealed through theoretical investigations using the density functional theory. The findings from the theoretical study are in good agreement with the experimental findings. The deposition mechanism during the nucleation and linear growth regime is studied thoroughly with an in situ quartz crystal microbalance illustrating a “substrate-enhanced growth” during the initial deposition cycles. The saturated growth rate of ∼0.28 Å per cycle is achieved. The as-grown material is then investigated as the photon-absorber layer in the sensitized solar cell application. The charge transfer processes are studied using surface photovoltage studies under monochromatic light and variable intensity white light using a vibrating Kelvin probe.