Electrical response of electron selective atomic layer deposited TiO2−x heterocontacts on crystalline silicon substrates

Integration of oxygen deficient sub-stoichiometric titanium dioxide (TiO2-x) thin films as the electron transporting-hole blocking layer in solar cell designs are expected to reduce fabrication costs by eliminating high temperature processes while maintaining high conversion efficiencies. In this paper, we conducted a study to reveal the electrical properties of TiO2-x thin films grown on crystalline silicon (c-Si) substrates by atomic layer deposition (ALD) technique. Effect of ALD substrate temperature, post deposition annealing, and doping type of the c-Si substrate on the interface states and TiO2-x bulk properties were extracted by performing admittance (C-V, G-V) and current-voltage (J-V) measurements. Moreover, the asymmetry in C-V and J-V measurements between the p-n type and n-n TiO2-x-c-Si heterojunction types were examined and the electron transport selectivity of TiO2-x was revealed.