Eliminating Mobility‐Thickness Dependence in Transparent Conductive Oxide Layer Growth: A Critical Nucleation Strategy

Abstract Carrier mobility is a key parameter for transparent conductive oxide (TCO) layers. However, it shows significant thickness‐dependent deterioration in the reports so far, making it challenging to obtain high‐quality ultrathin TCO films. Here, a critical nucleation strategy (cns) is proposed, i.e., manipulating nucleation status that matches the intended film thickness, to break the spell. 30, 20, and 10 nm‐thick cerium‐doped indium oxide (ICO) films are successfully fabricated with electron mobility values of 127, 119, and 108 cm 2 V −1 s −1 , respectively, which exceed twice that of the films with equal thickness obtained from the conventional solid‐phase crystallization approach. A novel film growth mode for fabricating a TCO layer with mobility independent of film thickness is proposed. It is claimed that an appropriate weakly‐crystallized as‐deposited film is a prerequisite for obtaining favorable crystallites with largely suppressed scattering from grain boundaries, ionized impurities, and film surface. Further, by implementing our 10 nm‐thick ICO film into silicon heterojunction architecture, a device efficiency of 25.16% is demonstrated, which is comparable to the reference cell using a 102 nm‐thick ICO film. This manifests a 90% indium reduction, indicating significant potential for future optoelectronic applications, particularly for the terawatt‐scale photovoltaic industry expansion.