Germanium made with nanopores
The properties of well-known semiconductor materials can be changed in spectacular ways by injecting them with microscopic holes. Silicon, for example, has already been made to glow with such nanostructures. Now two teams of scientists have found ways to also provide germanium with pores.
Chemists Gerasimos Armatas and Mercouri Kanatzidis from Michigan State University used a mixture of magnesium germanide, in which the semiconductor element is negatively charged, and germanium tetrachloride, in which it is positively charged . On the other hand, her colleagues led by Sarah Tolbert from the University of California in Los Angeles used small germanium clusters made up of nine atoms connected to form chains in independent experiments .
In both cases, spongy networks were formed whose energy structures had changed significantly: the porous semiconductors absorbed bluer light than conventional crystals. Exactly how large the shift is depends on the wall thickness of the sponges, which can be modified by gentle oxidation.
Manipulating the properties of semiconductors could prove useful for applications in solar cells, photodetectors or LEDs. Apparently, after silicon, germanium is also coming into the focus of scientists.