An international research team, including scientists from Forschungszentrum Jülich and the Paul Scherrer Institute in Switzerland, has created the first semiconductor laser consisting solely of Group IV elements. An international research team, including scientists from Forschungszentrum Jülich and the Paul Scherrer Institute in Switzerland, has created the first semiconductor laser consisting solely of Group IV elements.
The germanium-tin (GeSn) laser can be applied directly onto a silicon chip and thus creates a new basis for optical data transmission. "Signal transmission via copper wires limits the development of larger and faster computers due to the thermal load and the limited bandwidth of copper wires," said Professor Detlev Grützmacher, director of Jülich's Peter Grünberg Institute. "The clock signal alone synchronising the circuits uses up to 30% of the energy – energy which can be saved through optical transmission."
Typical semiconductor lasers for telecommunication systems are made from Group III-V elements – gallium arsenide for example and are costly and cannot be applied directly onto silicon. However, Group IV semiconductors – which includes silicon and germanium – can be integrated into standard manufacturing processes.
The scientists have created the semiconductor laser by combining germanium and tin – another Group IV element. "The high tin content is decisive for the optical properties," said PhD students Stephan Wirths. "For the first time, we were able to introduce more than 10% tin into the crystal lattice without it losing its optical quality."
According to the team, the Ge-Sn laser emits light with a wavelength of about 3µm and this may also allow its use in applications such as carbon compound detection.
Author
Graham Pitcher
Source: www.newelectronics.co.uk