Study of ohmic contact at Ti/ZnO interface by using electrical characteristics and KPFM analysis

Abstract In this paper, a negative barrier height at the interface of ZnO/Ti was studied using Kelvin probe force microscopy (KPFM) analysis. This result agrees with the metal-semiconductor Ohmic contact theory. Without any dopant, the pure ZnO thin films were deposited over integrated circuit compatible SiO 2 /p-Si silicon by the radio frequency (RF) sputtering method. Later, the ZnO thin films were annealed at 450 °C in a Nitrogen atmosphere. Annealing of the films produced better-quality contact as measured by a semiconductor parameter analyzer and the surface morphology, crystal structure, and optical properties as analyzed by atomic force microscopy (AFM), X-ray diffraction (XRD), and photoluminescence (PL) spectroscopy. The deposited thin films were analyzed to be crystalline, and edge emission occurred at 365 nm, as confirmed by XRD and PL measurements, respectively. The crystal size of the thin films is measured from XRD and are found to be 15.14 nm. The current-voltage characteristics were used to calculate the barrier height, which proves to be Ohmic in nature because of series resistance and barrier height in homogeneity. The calculated specific resistance of the device is 5 × 10 −5 Ω-cm 2 . This paper would encourage the use of an alternate method to calculate the barrier height of the device.