The effect of La2O3-incorporation in HfO2 dielectrics on Ge substrate by atomic layer deposition

Abstract We compared the electrical properties of HfO 2 , HfO 2 /La 2 O 3 , and La-doped HfO 2 gate insulators deposited on Ge substrate using an atomic layer deposition (ALD) process. TDMAH [tetrakis(dimethylamino)hafnium] and La(iprCp) 3 [tris(isopropyl-cyclopentadienyl) lanthanum] were employed as Hf and La precursors, respectively. Chemical compositions and binding structures were analyzed by X-ray photoelectron spectroscopy (XPS). Electrical properties were evaluated by capacitance–voltage (C–V) and current–voltage (I–V) measurements. We found that incorporation of La 2 O 3 near Ge can enhance the electrical properties of Ge MOS capacitors. The best electrical properties of 50 mV of hysteresis and mid ∼10 12  cm −2  eV −1 range interface states were found for the 400 °C-annealed HfO 2 /La 2 O 3 bilayer sample. These values are significantly better than those of ALD HfO 2 gate insulators on Ge. We attribute this to the formation of LaGeO x layers on the Ge surface, which reduces Ge O bonding.