Electrical characterization of Au/n-ZnO Schottky contacts on n-Si

Wide band gap semiconducting layer of n-type ZnO thin film was fabricated on n-type Si substrate with electrochemical deposition technique and the current-voltage (I-V) and the capacitance-voltage/frequency (C-V/f) characteristics of the structure have been measured at room temperature. The characteristic parameters of the structure such as barrier height, ideality factor and series resistance were determined from the current-voltage measurements. Also, Cheung functions and Norde method were used to plot the I-V characteristics and, to extract the characteristic parameters of the Schottky contact. It was seen that trap-filled space charge-limited current (SCLC) is the dominant transport mechanism at large forward bias. The capacitance measurements showed that the values of capacitance were almost independent of frequency up to a certain value of frequency whereas at high frequencies the capacitance decreased quickly. The higher values of capacitance at low frequencies were attributed to the excess capacitance resulting from the interface states in equilibrium with the ZnO that can follow the alternating current (ac) signal. (C) 2008 Elsevier B.V. All rights reserved.