Low-threshold electrically pumped ultraviolet random lasing from ZnO film prepared by pulsed laser deposition

ZnO films on silicon substrates are prepared by reactive sputtering and pulsed laser deposition, respectively. Their crystallinities, surface morphologies and photoluminescence actions are characterized using X-ray diffraction, scanning electron microscopy and photoluminescence spectroscopy correspondingly. Furthermore, the electrically pumped random laser actions of the two metal-insulator-semiconductor structured devices based on the sputtered and pulse laser deposition ZnO films respectively are comparatively investigated. It is found that the device fabricated using the pulse laser deposition ZnO film possesses a much lower threshold current for random lasing and higher output optical power. This is due to the fact that the pulse laser deposition ZnO film has much fewer defects, leading to remarkably lower optical loss during the multiple scattering within such a ZnO film.