Optical and Exciton Dynamical Properties of a Screw-Dislocation-Driven ZnO:Sn Microstructure

Screw dislocation plays a critical role in crystal growth and significantly affects the carrier dynamics process of luminescent semiconductor materials. In this paper, we report a novel screw-dislocation-induced ZnO:Sn hillock microstructure. The detailed growth process and possible formation mechanism of screw dislocation are demonstrated. The temperature-dependent photoluminescence reveals the free exciton recombination emission mechanism of the ZnO:Sn hillock microstructure. By comparing time-resolved photoluminescence spectra with those of two other samples without screw dislocations, it is found that the screw dislocation in the ZnO:Sn microstructures effectively decreases the carrier lifetime. In addition, UV Fabry-Perot lasing action is observed from the ZnO:Sn hillock microstructure, and the numerical simulation of the standing wave pattern and light intensity distribution further confirm the Fabry-Perot lasing mechanism. Therefore, ZnO:Sn can be utilized as a UV laser gain medium, and its optical properties can be modulated by screw dislocation.