Arizona State University researchers have created a new compound crystal material that promises to help produce advances in a range of scientific and technological¹ pursuits. ASU electrical engineering professor Cun-Zheng Ning says the material, called erbium（铒） chloride（氯化物） silicate², can be used to develop the next generations of computers, improve the capabilities³ of the Internet, increase the efficiency of silicon⁴-based photovoltaic（光电的） cells to convert sunlight into electrical energy, and enhance the quality of solid-state lighting⁵ and sensor⁶ technology.

Ning's research team of team of students and post-doctoral degree assistants help synthesize the new compound in ASU's Nanophotonics Lab in the School of Electrical, Computer and Energy Engineering, one of the university's Ira A. Fulton Schools of Engineering.

The lab's erbium research is supported by the U.S. Army Research Office and U.S. Air Force Office of Scientific Research. Details about the new compound are reported in the Optical Materials Express on the website of the Optical Society of America.

The breakthrough involves the first-ever synthesis of a new 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. It emits photons in the wavelength⁷ range of 1.5 micrometers, which are used in the optical fibers⁹ essential to high-quality performance of the Internet and telephones.

Erbium is used in doping optical fibers to amplify¹⁰ the signal of the Internet and telephones in telecommunications systems. Doping is the term used to describe the process of inserting low concentrations of various elements into other substances as a way to alter the electrical or optical properties of the substances to produce desired results. The elements used in such processes are referred to as dopants（参杂物） .

"Since we could not dope as many erbium atoms in a fiber⁸ as we wish, fibers had to be very long to be useful for amplifying¹¹ an Internet signal. This makes integrating Internet communications and computing¹² on a chip very difficult," Ning explains.

"With the new erbium compound, 1,000 times more erbium atoms are contained in the compound. This means many devices can be integrated into a chip-scale system," he says. "Thus the new compound materials containing erbium can be integrated with silicon to combine computing and communication functionalities on the same inexpensive silicon platform to increase the speed of computing and Internet operation at the same time."

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

Silicon does not absorb solar radiation with wavelengths¹³ longer than 1.1 microns, which results in waste of energy -- making solar cells less efficient.

Erbium materials can remedy（补救，治疗） 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 also help absorb ultraviolet light from the sun and convert it into photons carrying small amounts of energy, which can then be more efficiently¹⁴ converted into electricity by silicon cells. This color-conversion function of turning ultraviolet light into other visible colors of light is also important in generating white light for solid-state lighting devices.