Characteristics of aluminum-doped SnO₂ in various positions using super-cycle ALD

Metal oxide has attracted increasing interest because of its low resistivity, high transmittance, and flexibility. Among many metal oxide materials, tin dioxide (SnO₂), which has a low melting point and wide bandgap (3.6-4.0 eV), has properties suitable for applications such as transparent conductive oxides and thin film transistors. However, SnO₂has high oxygen vacancies (O_vac) and conductivity, reducing the on/off current ratio. To address this issue, we proposed an aluminum (Al) doping strategy using a super-cycle atomic layer deposition (ALD) process, which offers precise doping position control and uniform thickness. The effect of Al dopants used as the carrier suppressor in SnO₂was studied with different doping positions to investigate their impact on reducing O_vacand improving the off-current characteristics. The film properties were analyzed by AES, XRD, transmission electron microscopy, x-ray photoelectron spectroscopy, and Hall measurement, and the device property was analyzed by<i>I-V</i>measurements. The results revealed that Al doping in the middle region of the SnO₂thin film led to the most significant reduction in carrier concentration (1.31 × 10²⁰cm^-3) and O_vac(17.2%), thereby enhancing the SnO₂film properties and off-current characteristics. These findings demonstrate that precise doping control via super-cycle ALD can effectively modulate the electrical properties of SnO₂-based devices.