Zinc Oxide Nanowire Lasers Triple DVD Storage, Kill Bad Cells, Purify Water

A team of researchers at the Bourns College of Engineering at the University of California, Riverside has made a breakthrough in zinc oxide nanowire waveguide lasers. Zinc oxide nanowire lasers could be used to read and process much denser data on storage media. With zinc oxide, a DVD could store four to six hours of music instead of two hours. The research findings have been published in the July issue of Nature Nanotechnology.

In the past, zinc oxide nanowires couldn’t be used in real world light emission applications because of the lack of p-type, or positive type, material needed by all semiconductors. However, a team of researchers led by Jianlin Liu, a professor of electrical engineering, solved that problem by doping the zinc oxide nanowires with antimony, a metalloid element, to create the p-type material. The p-type zinc oxide nanowires were connected with n-type, or negative type, zinc oxide material to form a device called p-n junction diode. Powered by a battery, highly directional laser light emits only from the ends of the nanowires.

The research on zinc oxide nanowire waveguide lasers will impact more than just DVDs. For instance, the ultra-small laser light beam from a nanowire laser can penetrate a living cell, or excite or change its function from a bad cell to a good cell. The light could also be used to purify drinking water. In the area of photonics, the ultraviolet light could provide superfast data processing and transmission. Reliable small ultraviolet semiconductor diode lasers may help develop ultraviolet wireless communication technology, which is potentially better than state-of-the-art infrared communication technologies used in various electronic information systems.

In addition to Liu, the research team includes Sheng Chu, Guoping Wang, Jieying Kong, Lin Li and Jingjian Ren (UC Riverside); Weihang Zhou (Fudan University in China); Leonid Chernyak (professor of physics at the University of Central Florida); Yuqing Lin (University of Central Florida); and Jianze Zhao (Dalian University of Technology in China).

ZnO Nanowires Abstract from Nature Nanotechnology Journal

Ultraviolet semiconductor lasers are widely used for applications in photonics, information storage, biology and medical therapeutics. Although the performance of gallium nitride ultraviolet lasers has improved significantly over the past decade, demand for lower costs, higher powers and shorter wavelengths has motivated interest in zinc oxide (ZnO), which has a wide direct bandgap and a large exciton binding energy 1, 2, 3, 4, 5, 6. ZnO-based random lasing has been demonstrated with both optical and electrical pumping 7, 8, 9, 10, but random lasers suffer from reduced output powers, unstable emission spectra and beam divergence. Here, we demonstrate electrically pumped Fabry-Perot type waveguide lasing from laser diodes that consist of Sb-doped p-type ZnO nanowires and n-type ZnO thin films. The diodes exhibit highly stable lasing at room temperature, and can be modelled with finite-difference time-domain methods.

More info: Electrically pumped waveguide lasing from ZnO nanowires