Metal-induced trap states: the roles of interface and border traps in HfO2/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 HfO2 and at the HfO2/InGaAs interfaces are studied. The oxidation at Ti/HfO2 is found to create the highest density of interface and border traps, while a stable interface at the Mo/HfO2 interface leads to the smallest density of traps in our sample. The extracted values of Dit of 1.27 × 1011 eV−1cm−2 for acceptor-like traps and 3.81 × 1011 eV−1cm−2 for donor-like traps are the lowest reported to date. The density and lifetimes of border traps in HfO2 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.