Physical properties of silver oxide thin films by pulsed laser deposition: effect of oxygen pressure during growth

摘要

Silver oxide thin films have potential applications in ultra-high density optical non-volatile memories and in fluorescence imaging. In this paper, the physical properties of silver oxide thin films prepared at room temperature by the pulsed laser deposition (PLD) technique with varying oxygen pressure during growth are reported. The oxygen pressure in the growth chamber is varied between 9 and 50 Pa. The x-ray diffraction (XRD) analysis showed that all the films were polycrystalline. With increasing oxygen pressure in the growth chamber, it is observed that (i) the hexagonal Ag_2O transforms to monoclinic AgO, (ii) the grain size in the film increases from 59 to 200 nm, (iii) the surface roughness of the film increases from 9 to 42 nm, (iv) the resistivity of the films increases from 1 to 4 × 10~4 Ω m, (v) the surface work function of the films increases from 5.47 to 5.61 eV and (vi) the optical band gap of Ago thin films decreases from 1.01 to 0.93 eV. Raman spectroscopy on Ago thin films shows low wave number peaks corresponding to the stretching vibration of Ag—O bonds. This study shows that single phase Ago thin films, a requirement for plasmonic devices, can be prepared at room temperature by the PLD technique with an oxygen pressure of 20 Pa.