Structural, electrical and optical properties of transparent conducting Si-doped ZnO thin films grown by pulsed laser deposition

Thin silicon doped zinc oxide films were ablated onto borosilicate glass substrates by pulsed laser deposition of a bulk ZnO target doped with 2 wt% silicon. The rotating target was irradiated at low ambient oxygen pressures by a KrF Excimer laser (Lambda physics LPX 300) emitting pulses of 0.18 ns in length, with frequency of 10 Hz, at a wavelength of 248 nm and with energy fluence of 1-2 J/cm2. The temperature of the substrate was changed from room temperature to 500˚C at the fixed oxygen pressure of 5 mTorr. The partial oxygen pressure was varied from 0.01 to 500 mTorr at the substrate temperature of 300˚C. The growth rate was differed by varying target-to-substrate distance from 50 to 70 mm at 5 mm increment. The films were characterised by atomic force microscopy, Hall effect measurements, ellipsometry, laser microscope, X-ray diffraction, spectrophotometry, four point probe and scanning electron microscopy. Deposition parameters such as, the substrate temperature, oxygen pressure, target-to-substrate distance and the number of pulses were varied to maximise optical transmittance and minimise resistivity. The optimum deposition circumstances yielded a film of resistivity of 4.12×10-4 Ωcm and a transmittance of 89%