Charge trapping and interface characteristics of thermally evaporated HfO2

Charge trapping and interface characteristics of hafnium oxide (HfO2) films, grown by standard thermal evaporation, were investigated. High frequency capacitance–voltage and conductance measurements were carried out at various temperatures on aluminum gate metal–oxide–semiconductor capacitors, annealed at 450°C. A hysteresis below 30mV was observed. Electrical data show, that charge trapping in HfO2 initially increases with decrease in temperature while it shows a turnaround phenomenon when the temperature is decreased further. Interface state density distribution observed at low temperatures suggests that charge-trapping behavior of these films is mostly due to shallow traps at the interface.