Effects of thickness on 1/f noise of Co and In co-doped ZnO

Abstract

We have investigated the effects of thickness on the electrical properties of Co 2% and In 1% co-doped ZnO films (CIZO) grown on glass substrates at room temperature by Radio Frequency (RF) magnetron sputtering technique. The sheet resistance R sh [Ω], the resistivity ρ [Ω.cm], and the 1/f noise have been analysed as a function of thickness from 50 nm to 450 nm. The electrical properties and 1/f fluctuation noise were carried out by using four-point probe method. In order to reduce the contacts problems, we applied a constant current through the pair of inner electrodes and observed the voltage fluctuations across the pair of outer electrodes. We characterized the noise below 100 kHz and obtained classical 1/f spectra. We attempted to verify the validity of Hooge's empirical relation and to test its usefulness as a diagnostic tool. The results show that the noise coefficient K [cm2/03A9] = C us / R sh increases with the thickness twhich indicates that mobility and the noise parameter α H shrinks with a shrinking thickness. We have also studied the structural and optical properties of these films.