With laser emission in the near-UV, zinc oxide (ZnO) could be the next big thing in lasing materials—if it behaved well enough. While random lasing (arising from multiple scattering in disordered structures) is easiest to achieve with ZnO, researchers have also created single Fabry-Perot (F-P) nanowire lasers and whispering-gallery-mode nanodisks–although the F-P and nanodisk lasers were optically pumped. Now, scientists at Zhejiang University (Hangzhou, China) have caused ZnO to lase via electrical pumping in an arrangement where ZnO nanorod arrays embedded in silicon dioxide (SiO2) are fabricated on silicon (Si) and capped with a gold electrode. The resulting metal-insulator-semiconductor structure causes random lasing in the nanorods when pumped at 5 V or more.
First, vertically aligned ZnO nanorod arrays were grown on silicon; next, SiO2 was deposited via a sol-gel process; finally, a gold electrode was deposited on top of the structure, and another electrode fabricated on the back of the Si. The nanorods were very uniform in length (about 2 µm) and ranged from 40 to 80 nm in diameter. The wavelength spectrum emitted by the laser changed constantly—a result of the random process. The approach is interesting, however, in that it could be applied in the future to other ZnO lasing structures such as single F-P nanowires. Contact Deren Yang at [email protected].
