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

Abstract

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, SnO2 has high oxygen vacancies (Ovac) 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 SnO2 was studied with different doping positions to investigate their impact on reducing Ovac and 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-V measurements. The results revealed that Al doping in the middle region of the SnO2 thin film led to the most significant reduction in carrier concentration (1.31 x 1020cm-3) and Ovac (17.2%), thereby enhancing the SnO2 film 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.