Sep 29 2010
The electronic bandgap is an intrinsic property of semiconductors that to a large extent determines their optical properties, such as their emission color. Having the ability to adjust the bandgap can be extremely useful for developing semiconductor nanocrystals with novel properties and applications in optoelectronics, photovoltaics and biological imaging.
Several approaches have been used to tune the bandgap of a semiconductor. One common approach involves altering the crystal size, and many groups have already demonstrated this technique in experiments. The bad news is that in many applications, semiconductor nanocrystals must be very small in order to produce the desired properties.
Another approach is to change the crystal composition. This method usually involves alloying together two semiconductors with different bandgap energies, but research in this area is in its infancy. Ming-Yong Han and co-workers from the A*STAR Institute of Materials Research and Engineering1 in Singapore have now demonstrated an example of composition-based bandgap engineering using an alloy of cadmium selenide (CdSe) and zinc selenide (ZnSe). By controlling the proportions of these two compounds, the researchers produced high-quality nanocrystals that exhibit interesting optical properties not observed in the parent semiconductors.
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