Change of the trap energy levels of the atomic layer deposited HfLaO _x films with different la concentration

Ultrathin HfO2 and HfLaO_x films with La/ (Hf+La) ratios of 42%, 57%, and 64% were synthesized with an atomic layer deposition process. By measuring the leakage current at different temperatures, the conduction mechanism of HfO2 and HfLaO_x films was shown to follow the Poole-Frenkel emission model under a gate injection condition. Based on the temperature and field-dependence measurements, the intrinsic trap energy levels were found to be 1.42, 1.34, 1.03, and 0.98 eV for the HfLaO_x samples with La/ (Hf+La) ratios of 0%, 42%, 57%, and 64%, respectively, showing a decreasing behavior as the La content increased.