University of Arkansas engineering professor Shui-Qing “Fisher” Yu and a team of researchers, in collaboration with a semiconductor equipment manufacturer, have fabricated an “optically pumped” laser made of the alloy germanium tin grown on silicon substrates.

The augmented material could lead to the development of fully integrated silicon photonics, including both circuits and lasers, and thus faster micro-processing speed at much lower cost.

Superchip in the making

Yu and his colleagues’ contribution to this effort is an optically pumped laser using germanium tin. Optically pumped means the material is injected with light, similar to an injection of electrical current. Germanium tin holds great promise as a semiconducting material for future optical integration of computer chips, as it harnesses efficient emission of light, which the standard material for making computer chips–silicon–cannot do. In recent years, materials scientists and engineers, including Yu and several of his colleagues on this project, have focused on the development of germanium tin, grown on silicon substrates, to build a so-called optoelectronics “superchip” that can transmit data much faster than current chips.

“We reduced the laser threshold 80 percent at a lasing operation temperature up to 110K,” Yu said. “This is significant progress compared with the previously reported best result and shows that germanium tin holds great promise as an on-chip laser.”

 
germanium research Fisher Yu (cr) Figure 1: Fisher Yu, University of Arkansas  

On this project, Yu and his colleagues worked with ASM America’s research and development staff which developed the growth methods. ASM’s methods produce low-cost and high-quality germanium tin in an industry standard chemical vapour deposition reactor.