Electrical properties of Al2O3 film deposited at low temperatures

Amorphous Al2O3 films were deposited on p-Si by rf magnetron sputtering to investigate their potential as a gate dielectric in organic thin film transistors (OTFTs). The deposition was performed at room temperature, 200 and 300 C using Al2O3 and Al targets. Achieved Al2O3 films have higher capacitance values than thermally grown SiO2 as characterized by capacitance-voltage measurements. It is also found from current-voltage and roughness measurements that the leakage current and the surface roughness can be least when the films are deposited at room temperature. The capacitance of the film obtained from the Al2O3 target appears higher than that of the AI,03 film from the Al target while the results of electrical breakdown are opposite. These room temperature processes are promising for applications to the gate dielectrics of organic TFTs. (C) 2002 Elsevier Science Ltd. All rights reserved.