Metal-Induced Trap States: The Roles of Interface and Border Traps in HfO/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 and at the HfO/InGaAs interfaces are studied. The oxidation at Ti/HfO is found to create the highest density of interface and border traps, while a stable interface at the Mo/HfO interface leads to the smallest density of traps in our sample. The extracted values of D of 1.27 × 10 eVcm for acceptor-like traps and 3.81 × 10 eVcm for donor-like traps are the lowest reported to date. The density and lifetimes of border traps in HfO 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.