Photoconductivity of self-assembled ZnO nanoparticles synthesized by organometallic chemistry

We report on the photoconductivity properties of devices based on ZnO nanoparticles for UV detection. The nanoparticles were synthesized by organometallic chemistry, self-assembled on Si substrates covered by inter-digited metallic electrodes and annealed at 200 degrees C. The photoconductivity of these devices was measured for wavelengths ranging from 300 to 600 nm. The sensitivity of our samples at 350 nm excitation wavelength is about 1 A cm(2) W-1, or 1200 A W-1, with a visible rejection of 150. The photoconductivity strongly depends on pressure and is one order of magnitude larger under vacuum than at atmospheric pressure. Transient photoconductivity characteristics at atmospheric pressure and under vacuum are fitted using stretched exponential functions and quantitatively analysed. These results show the potential use of chemically prepared ZnO nanoparticles for UV and/or gas detection.