Study on the Physical Properties of Pulsed Laser Deposited Doped Copper Oxide (Cu2 O) Thin Films for Optical Device Applications

Abstract

Cuprous oxide, (Cu2O) is a promising p-type semiconductor, finds practical applications in a wide range of optoelectronic devices. In this paper, pulsed laser deposition technique is employed to deposit doped Cu2O thin films. The influence of doping of silver (Ag), aluminium (Al) and co-doping of (Ag+Al) in Cu2O thin films is illustrated. X-ray diffraction pattern depicts cubic crystal structure and polycrystalline nature of grown thin films, having small crystallite size (~50 nm). Atomic force microscopy (AFM) obtained surface images of the films portrait uniform grain morphology with low surface roughness. The room temperature optical characterizations of the thin films, the transmittance versus wavelength in the UV-Visible region exhibits low transmission values upto 10–20%, illustrates the large absorption coefficient (α), numerical values varying from 104 to 105cm-1 for doped Cu2O films. The large values of absorption coefficient facilitate the optical and photovoltaic applications of the doped Cu2O films. The addition of dopant species Ag and Al, the optical band gap is increased and it varies in the range of 2.65−2.84 eV. The increased energy gap is attributed to the substitution of Al and Ag ions for the oxygen ions reduce the width of valence band to widen the energy gap. The I−V characteristics plot obtained at room temperature indicates low electrical resistivity (ρ ~ 10-2Ω- cm) of the films. The obtained results are of high relevance and indicate potential applications of the grown thin films in semiconductor devices such as solar cells, photodetectors and optical sources