Leakage current characteristics and the energy band diagram of Al/ZrO2/Si0.3Ge0.7hetero-MIS structures

Zirconium oxide (ZrO2) films have been deposited on Ge-rich SiGe heterolayers at 150 ?C by the microwave plasma enhanced chemical vapour deposition (PECVD) technique using zirconium tetra-tert-butoxide. The possible conduction mechanisms in deposited ZrO2 films have been investigated at both room and high temperature. It is found that the conduction mechanism is dominated by Schottky emission at a low electric field (E 1.2 MV cm?1). The extracted trap energy is about 0.78 eV from the conduction band of ZrO2. It is shown that the current in ZrO2 films exhibits strong temperature dependence at a low electric field. The trapping behaviour of the charge carriers in thin ZrO2 gate dielectric stacks during constant gate voltage stress of metal?oxide?semiconductor capacitors has also been investigated.