News Article
Multifaceted laser technology could kill viruses and Improve DVDs
Scientists are claiming that zinc oxide nanowire waveguide lasers can offer smaller sizes, lower costs, higher powers and shorter wavelengths than conventional gallium nitride UV lasers.
A team led by Jianlin Liu from the University of California, Riverside Bourns College of Engineering has made a discovery in semiconductor nanowire laser technology that could potentially do everything from kill viruses to increase storage capacity of DVDs.
Ultraviolet semiconductor diode lasers are widely used in data processing, information storage and biology. Their applications have been limited, however, by size, cost and power. The current generation of ultraviolet lasers is based on GaN, but Jianlin Liu and his colleagues have made a breakthrough in zinc oxide (ZnO) nanowire waveguide lasers, which can offer smaller sizes, lower costs, higher powers and shorter wavelengths.
Until now, ZnO nanowires couldn’t be used in light emission applications because of the lack of p-type material needed by all semiconductors. This problem was overcome by doping the ZnO oxide nanowires with antimony to create the p-type material.
The p-type ZnO nanowires were connected to the n-type ZnO material, which was grown on a c-sapphire substrate, to form the p-n junction diode. Powered by a battery, highly directional laser light emits only from the ends of the nanowires.
“People in the zinc oxide research community throughout the world have been trying hard to achieve this for the past decade,” Liu said. “This discovery is likely to stimulate the whole field to push the technology further.”
The discovery could have a wide-range of impacts.
For information storage, the zinc oxide nanowire lasers could be used to read and process much denser data on storage media such as DVDs because the ultraviolet has shorter wavelength than other lights, such as red. For example, a DVD that would normally store two hours of music could store four or six hours using the new type of laser.
For biology and medical therapeutics, 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.
For 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.
Figure: From left, Guoping Wang, Jianlin Liu and Sheng Chu
While Liu and the students in his laboratory have demonstrated the p-type doping of zinc oxide and electrically powered nanowire waveguide lasing in the ultraviolet range, he said more work still needs to be done with the stability and reliability of the p-type material.
Further details of this work can be found in the paper “Electrically pumped waveguide lasing from ZnO nanowires” by Sheng Chuet al published in Nature Nanotechnology (2011). DOI: doi:10.1038/nnano.2011.97
The work was carried out in conjunction with researchers at Fudan University in China, the University of Central Florida and the Dalian University of Technology in China.
The work on the ZnO device was in part supported by Army Research Office Young Investigator Program and the National Science Foundation. The work on p-type ZnO was supported by the US Department of Energy.
