SiO2 Capped-ZnO nanorods for enhanced random laser emission

•SiO2 capped ZnO nanorods achieved by combined method of RF magnetron sputtering and chemical bath deposition (CBD).•100 nm of SiO2 capped on ZnO nanorods showed superior random lasing.•Numerical simulation using finite element showed improved efficiency of the nanorods resonators by modified guided mode.•Potential candidate for electrically pumped random laser. In this paper, we report SiO2 capped Zinc Oxide nanorod array (SiO2 capped-ZnO NAs) for enhancing UV random lasing emissions at room temperature. A simple method chemical bath deposition (CBD) under optimum conditions was used to from vertically aligned ZnO NAs on glass substrate at room temperature. The random lasing emission intensity increased 30 times compared to bare ZnO NAs (without SiO2) at the same pump power. The best sample with 100 nm of SiO2 capping showed superior lasing, whereby the random lasing peaks almost suppressed the spontaneous emission peak completely. This enhancement was attributed to improved light confinement inside the ZnO NAs resonators which increases the performance of the stimulated light emission within the gain medium. To further understand the mechanism behind the enhanced lasing properties, a numerical simulation using finite-element method was performed. The simulation results showed SiO2 capped-ZnO nanorod lead to an enhancement of light confinement within the resonators.