Novel process to integrate single-crystal semiconductor into an optical fibre

Washington, March 13 : An international team of researchers has come up with a process to grow a single-crystal semiconductor inside the tunnel of a hollow optical fibre.

The research team - comprising experts from Penn State University in the US and the University of Southampton in the UK - says that the device adds new electronic capabilities to optical fibres, whose performance in electronic devices like computers typically is degraded by the interface between the fibre and the device.

Their work attains significance as optical fibres - used in a wide range of technologies that employ light such as telecommunications, medicine, computing, and remote-sensing devices - are ideal media for transmitting many types of signals.

The latest development builds on previous research by the same team wherein optical fibres were combined with polycrystalline and amorphous semiconductor materials for the first time, in order to create an optical fibre that also has electronic characteristics.

The researchers say that their latest work, suggesting that a single-crystal semiconductor also can be integrated into an optical fibre, may lead to further improvements in the characteristics of optical fibres that are used in many areas of science and technology.

"For most applications, single-crystal semiconductor materials have better performance than polycrystalline and amorphous materials. We have now shown that our technique of encasing a single-crystal semiconductor within an optical fiber results in greater functionality of the optical fiber, as well," said John Badding, associate professor of chemistry at Penn State.

The team used a high-pressure fluid-liquid-solid approach to build the crystal inside the fibre. First, the scientists deposited a tiny plug of gold inside the fibre by exposing a gold compound to laser light, and then introduced silane, a compound of silicon and hydrogen, in a stream of high-pressure helium.

When the fibre was heated, the gold acted as a catalyst, decomposing the silane, and thus allowed silicon to deposit as a single crystal behind the moving gold catalyst particle, forming a single-crystal wire inside the fibre.

"The key to joining two technologies lies not only in the materials, but also in how the functions are built in. We were able to embed a nanostructured crystal into the hollow tube of an optical fibre to create a completely new type of composite device," said Pier Sazio, senior research fellow in the Optoelectronics Research Centre at the University of Southampton.

The researchers see the potential to make the technology faster and more efficient.

"At present, we still have electrical switches at both ends of the optical fiber. If we can get to the point where the electrical signal never leaves the fiber, it will be faster and more efficient," said Badding.

The development of the single-crystal device will be described in a paper to be published later this month in the journal Advanced Materials.

ANI