© 2018, Springer-Verlag GmbH Germany, part of Springer Nature.The effects of the TiO2 high-k insulator material on Au/n-GaAs/Ti/Au Schottky barrier diodes have been studied by means of the numerical simulation and experimental results at room temperature. The Atlas-Silvaco-TCAD numerical simulator has been used to explain the behavior of different physical phenomena of Schottky diode. The experimental values of ideality factor, barrier height, and series resistance have been determined by using the various techniques such as Cheung’s method, forward bias lnI–V and reverse capacitance–voltage behaviors. The experimental ideality factor and barrier height values have been found to be 4.14 and 0.585 eV for Au/n-GaAs/Ti/Au Schottky barrier diode and 4.00 and 0.548 eV for that structure with 16 nm thick TiO2 film and 3.92, 0.556 eV with 100 nm thick TiO2 film. The diodes show a non-ideal current–voltage behavior that of the ideality factor so far from unity. The extraction of Nss interface distribution profile as a function of Ec–Ess is made using forward-bias I–V measurement by considering the bias dependence of ideality factor, the effective barrier height, and series resistance for Schottky barrier diodes. The Nss calculated values with consideration of the series resistance are lower than the calculated ones without series resistance. The current–voltage results of diodes reveal an abnormal increase in leakage current with an increase in thickness of high-k interfacial insulator layer. However, the simulation agrees in general with the experimental results.