Control of Transfer Characteristics of Atomic Layer Deposited Al-Doped SnO₂ Thin Film through a Post-Annealing Process

In this paper, changes in transfer characteristics for an Al-doped SnO2 thin film using the annealing process was studied. Generally, as-deposited SnO2 thin film has electrical properties similar to those of the conductor due to high carrier concentration. However, various electrical properties such as on/off current ratio could be obtained as Al was doped and the annealing process was performed in an air atmosphere. As a result of XPS analysis, it was confirmed that the concentration of oxygen vacancy concentration decreased when the Al-doped SnO2 thin film was annealed. Compared to the as-deposited Al-doped SnO2 thin film, the annealed Al-doped SnO2 thin film had superior channel characteristics because the oxygen vacancy concentration in the SnO2 thin film was lowered by the oxygen atom diffusion during the annealing process. This is due to the lower carrier concentration. As a result of analyzing the electrical properties of the annealed Al-doped SnO2 thin film, that film annealed at 500 °C, an on/off current ratio of 106 was obtained. And the field effect mobility was also 1.56 cm2 Vs−1.