One-Step Laser-Induced Oxidation and Doping for Tailored p-Type Conversion of Al-Doped TiO₂

The lack of p-type conductivity in metal oxide semiconductors presents the major limitation for their integration into complementary metal-oxide-semiconductor (CMOS) technology, which requires both n-type and p-type semiconductors for balanced and efficient operation. Titanium dioxide (TiO₂) is known for its wide-gap n-type semiconductor characteristics, but it is challenging to convert it into a p-type semiconductor. This study focuses on the semiconducting type conversion of TiO₂ via laser-assisted oxidation and doping integration, enabling simultaneous Ti oxidation to form TiO₂ and type-conversion-friendly Al doping in a single step. When the laser power exceeds a specific threshold, Al cations from the underlying Al₂O₃ layer diffuse into the TiO₂ lattice. This selective incorporation of Al converts the intrinsic n-type conductivity of TiO₂ to p-type by substituting Ti⁴⁺ with Al³⁺. The formation of TiO₂ and the incorporation of Al dopants are confirmed using X-ray Photoelectron Spectroscopy and Energy Dispersive Spectroscopy Transmission Electron Microscopy. In addition, the fabrication of laser-oxidized Al-doped TiO₂ thin-film transistors confirms that Al doping improves hole current and photostability. The laser-induced Al-doped TiO₂ offers an easy, simple, efficient, and controllable fabrication method for CMOS technology and advanced electronic devices.