Voltage- and Frequency-Dependent Electrical Characteristics and Interface State Density of Ni/ZnO Schottky Diodes

S.M. Faraza, Z. Tajwara, Q. ul Wahabb, A. Ulyashinc, R. Yakimovab aDepartment of Electronic Engineering, NED University of Engineering and Technology, University Road, 75270, Karachi, Pakistan bDepartment of Physics, Chemistry and Biology, Linköping University, 58183 Linköping, Sweden cSINTEF Industry Forskingsveien 1, 0314 Oslo, Norway

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Frequency and voltage dependent electrical characteristics are reported for Ni/ZnO Schottky diodes. Schottky diodes are realized from nano-structured ZnO thin films grown by DC magnetron sputtering. Electrical characterizations are performed by current-voltage (I-V), capacitance-voltage (C-V) and conductance-voltage (G/ω-V) measurements. The diode parameters are extracted, such as barrier height (ϕB), ideality factor (n) and carrier concentration (ND). The diodes exhibited a non-linear rectifying behaviour with a barrier height of 0.68 eV and an ideality factor greater than unity. Charge transport mechanism and possible reasons responsible for non-idealities are investigated. The density of interface states (NSS) below the conduction band are extracted from the measured values of I-V and C-V as a function of EC-ESS. From EC-0.51 to EC-0.64 eV below the conduction band edge, the interface state density NSS is found to be in the range 1.74×1012-1.87×1011 eV-1 cm-2. The interface states density obtained from capacitance-frequency (C-f) characteristics varied from 0.53×1012-0.12×1012 eV-1 cm-2 from EC-0.82 eV to EC-0.89 eV below the conduction band. A complete description of current transport and interface properties is important for the realization of good quality Schottky diodes and for the design and implementation of high performance electronic circuits and systems.

DOI:10.12693/APhysPolA.141.99 topics: ZnO Schottky diode, Interface states, DC magnetron sputtering\\vs*{2pt}