Characterization of thin and ultrathin transparent conducting oxide (TCO) films and TCO‐Si interfaces with XPS, TEM and ab initio modeling

Interfaces play an important role in solar cell heterostructures, especially when film thicknesses decrease. In this work, we use XPS, transmission electron microscopy (TEM) and density functional theory (DFT) to study both the film and the film–Si interface of electron beam deposited indium tin oxides (ITO) and pulsed laser deposition (PLD) deposited ZnO on p‐Si (100). Vacuum evaporation of ITO resulted in a film that contained elemental Sn and In which oxidized after annealing at 300 °C for 30 min. Ar etching of the HF‐treated Si substrate in the PLD deposition chamber caused an increase of the interfacial oxide thickness independently of the deposition temperature as a result of Ar etching‐induced dangling bonds. Deposition as well as annealing at elevated temperature also increases the interfacial oxide thickness for both ITO‐Si and ZnO‐Si systems.