Electrically pumped random lasing in ZnO-based metal-insulator-semiconductor structured devices: Effect of ZnO film thickness

Abstract

In our previous report [Ma et al., Appl. Phys. Lett. 91, 251109 (2007)], electrically pumped random lasing (RL) from polycrystalline ZnO films has been realized by means of metal-insulator-semiconductor (MIS) structures based on ZnO films on silicon substrate. Herein, we investigate the effect of ZnO film thickness on the threshold current and output power of RL from the ZnO-based MIS structured devices. It is found that the RL threshold current increases with the increase of ZnO film thickness. Moreover, the output power of RL decreases with the increase of ZnO film thickness at small injection current, while it increases with the ZnO film thickness at large injection current. The mechanisms underlying the above-mentioned results have been tentatively explored in terms of the two ingredients of RL, i.e., multiple light scattering and optical gain.