Saturday, 02 August 2014
masthead+quote+image
Advanced search

Researchers look to silicon semiconductor alternative

Researchers in the US believe they’ve overcome a major hurdle in developing a functional alternative to the silicon semiconductor.

Silicon semiconductors are ubiquitous in modern electronics but these devices have limitations, including a failure to operate properly at very high temperatures.

One promising alternative is a semiconductor made from aluminium and nitrogen to form aluminium nitride (AlN), which is stronger and more stable than its silicon counterpart, can function at high temperatures, is piezoelectric, and is transparent to, and can emit, visible light.

Conventional processes for producing AIN layers run at temperatures as high as 1150 degrees Celsius, and offer limited control over the thickness of the layers. Now a new technique is claimed to offer a way to produce high-quality aluminium nitride (AlN) layers with atomic-scale thickness and at half the temperature of other methods.

Neeraj Nepal and colleagues of the US Naval Research Laboratory in Washington, DC, formed AIN layers using atomic layer epitaxy (ALE), in which materials are ‘grown’ layer-by-layer by sequentially employing two self-limiting chemical reactions onto a surface.

‘For instance to grow aluminium nitride, you would inject a pulse of an aluminium precursor into the growth zone where it would coat all surfaces,’ Nepal said in a statement.

‘After purging any excess aluminium precursor away, you would then ‘build’ the crystal by injecting a pulse of the nitrogen precursors into the growth zone, where it reacts with the aluminium precursor at the surface to form a layer of AlN. Then you’d purge any excess nitrogen and reaction products away and repeat the process.’

With this process, the researchers produced a material with qualities similar to those synthesised at much higher temperatures, but under conditions that allow it to be integrated in new ways for the fabrication of devices for technologies such as transistors and switches.

Nepal said the work expands the potential for new advanced specialty materials that could be used in applications including next-generation high-frequency radio frequency electronics, such as those used for high-speed data transfer and cell phone services.

The work is described in Applied Physics Letters in an article entitled, Epitaxial Growth of AlN Films via Plasma-assisted Atomic Layer Epitaxy.


Have your say

Mandatory
Mandatory
Mandatory
Mandatory

My saved stories (Empty)

You have no saved stories

Save this article

Digital Edition

The Engineer July Digi Issue

Poll

London Mayor Boris Johnson is lobbying for a £10 additional charge for diesel cars to drive into Central London by 2020, and for road tax on diesel cars and all pre-2006 cars to be increased, to counter air pollution. What option most closely matches your opinion on this?

Previous Poll

Europe's largest tidal array in the Pentand Firth off Orkney will eventually generate up to 86MW of power. What will it take for tidal energy to make an appreciable contribution to the UK's energy needs?

Read and comment on the results here