Light Emitting Thin Films Containing Germanium Quantum Nanocrystals

The recent observation of light emission from porous silicon and from germanium nanocrystals in a silicon dioxide matrix has given a great boost to the field of quantum confined structures. It has been suggested that the formation of quantum wires in porous silicon is responsible for the observed emission. The confinement effects in quantum nanocrystals are even more pronounced. In preliminary measurements, SMI has noticed photoluminescence emission (600-900 nm) from silicon Si/SiO2. Ge as smaller effective hole and electron masses and a larger dielectric constant than Si, and as such should exhibit a greater blue shift for a given nanocrystal size. These films may be ideal for the observation and development of confinement effects in germanium quantum nanocrystals. The germanium particles are surrounded by wide bandgap silicon dioxide, which forms an ideal potential barrier. SMI will develop a deposition and processing technology to form, control, and study germanium nanocrystals for luminescence. Later work will investigate electroluminescence by AC excitation.