Metal-Induced Trap States: The Roles of Interface and Border Traps in HfO 2 /InGaAs.

By combining capacitance-voltage measurements, TCAD simulations, and X-ray photoelectron spectroscopy, the impact of the work function of the gate metals Ti, Mo, Pd, and Ni on the defects in bulk HfO 2 and at the HfO 2 /InGaAs interfaces are studied. The oxidation at Ti/HfO 2 is found to create the highest density of interface and border traps, while a stable interface at the Mo/HfO 2 interface leads to the smallest density of traps in our sample. The extracted values of D it of 1.27 × 10 11 eV -1 cm -2 for acceptor-like traps and 3.81 × 10 11 eV -1 cm -2 for donor-like traps are the lowest reported to date. The density and lifetimes of border traps in HfO 2 are examined using the Heiman function and strongly affect the hysteresis of capacitance-voltage curves. The results help systematically guide the choice of gate metal for InGaAs.