Researchers claim crystal could be technology enhancing

17 November 2011

ASU electrical engineering professor Cun-Zheng Ning believes the material, called erbium chloride silicate, can be used to develop the next generations of computers, improve the capabilities of the internet, increase the efficiency of silicon-based photovoltaic cells and enhance the quality of solid-state lighting and sensor technology.

The breakthrough involves the first-ever synthesis of an erbium compound in the form of a single-crystal nanowire, which has superior properties compared to erbium compounds in other forms.

Erbium is one of the most important members of the rare earth family in the periodic table of chemical elements as it emits photons in the wavelength range of 1.5 micrometres, which are used in the optical fibres essential to high-quality performance of the internet and telephones.

Erbium is used in doping optical fibres to amplify the signal of the internet and telephones in telecommunications systems. Doping alters the electrical or optical properties of materials to produce the desired results.

‘Since we could not dope as many erbium atoms in a fibre as we wished, fibres had to be very long to be useful for amplifying an internet signal. This makes integrating internet communications and computing on a chip very difficult,’ Ning said.

‘A thousand times more erbium atoms are contained in the new compound. This means many devices can be integrated into a chip-scale system,’ he added.

Ning said this is why the materials containing erbium can be integrated with silicon to combine computing and communication functionalities on the same silicon platform to increase the speed of computing and internet operation simultaneously.

Erbium materials can also be used to increase the energy-conversion efficiency of silicon solar cells.

Silicon does not absorb solar radiation with wavelengths longer than 1.1 microns, which results in waste of energy — making solar cells less efficient.

Erbium materials are reported to be able to remedy the situation by converting two or more photons carrying small amounts of energy into one photon that is carrying a larger amount of energy. The single, more powerful, photon can then be absorbed by silicon, thus increasing the efficiency of solar cells.

Erbium materials can also help absorb ultra-violet light from the sun and convert it into photons carrying small amounts of energy, which can then be more efficiently converted into electricity by silicon cells.