Structural, optical and electrical properties of reactively sputtered Ag_2Cu_2O_3 films

摘要

Ag_2Cu_2O_3 thin films were deposited on glass substrates by RF magnetron sputtering of an equiatomic silver-copper target ( Ag_(0.5)Cu_(0.5)) in reactive Ar-O_2 mixtures. The reactive sputtering was done at varying power, oxygen flow rate and deposition temperature to study the influence of these parameters on the deposition of Ag_2Cu_2O_3 films. The film structure was determined by X-ray diffraction, while the optical properties were examined by spectrophotometry (UV-vis-NIR) and photoluminescence. Furthermore, the film thickness and resistivity were measured by tactile profilometry and 4-point probe, respectively. Additional mobility, resistivity and charge carrier density Hall effect measurements were done on a few selected samples. The best films in terms of stoichiometry and crystallography were achieved with a sputtering power of 100 W, oxygen and argon flow rates of 20 sccm (giving a deposition pressure of 1.21 Pa) and a deposition temperature of 250 ℃ The optical transmittance and photoluminescence spectra of films deposited with these parameters indicate several band gaps, most prominently, a direct one of around 2.2 eV. Electrical characterization reveals charge carrier concentrations and mobilities in the range of 10~21-10~(22) cm~(-3) and 0.01-0.1 cm~2/Vs, respectively.