Semiconductor wire built into an optical fibre

Optoelectronics specialists at Penn State University in the US and the University of Southampton, UK, have developed a process for growing single-crystal semiconductor wires inside a hollow-core optical fibres.

Optical fibres, which now form the backbone of high-speed terrestrial communications networks, are idea media for transmitting many types of signals. It therefore makes sense to integrate electrical and optical switching into the same devices.

Single-crystal semiconductor wires are grown inside a hollow-core optical fibre via a high pressure fluid-liquid-solid approach. In this way optical and electrical switching can be integrated into the same devices

Bryan Jackson, Pier Sazio and John Badding use a fluid-liquid-solid approach to grow single-crystal material inside a hollow fibre. They first deposit a plug of gold inside the core, and then introduce silane in a stream of high pressure helium. The gold decomposes the silane, and allows its constituent silicon to deposit as a single crystal behind the moving plug. The result is a semiconductor wire that runs through the core of the fibre.

“Semiconductor device physics and technology has made an enormous impact in computers and optoelectronics,” says Sazio, who is a senior research fellow in Southampton. “The marriage of these two technologies means that we now have a new toolbox with which we can explore completely new devices hybridised inside this new composite. Examples include optical and electrical switches inside optical fibres.”

Sazio describes the work in terms of a proof-of-principle that the researchers could grow single-crystal material inside an optical fibre using a catalysis method. “As to whether that’s scalable, we are not sure at this point,” he says. ‘But we will also investigate other methods that could lend themselves more towards manufacturability.”

Taking this development to the next level will involve containing the electronics entirely within an optical device. “At present, we still have electrical switches at both ends of the optical fibre,’ says Badding. “If we can get to the point where the electrical signal never leaves the fibre, it will be faster and more efficient.”

Further reading: “Single Crystal Semiconductor Wires Integrated into Microstructured Optical Fibers”, Jackson et al., Adv. Materials 20, 1135 (2008).

Figure: Single-crystal semiconductor wires are grown inside a hollow-core optical fibre via a high pressure fluid-liquid-solid approach. In this way optical and electrical switching can be integrated into the same devices (source: Pier Sazio).

Article first published in Nanomaterials News.