Synthesis of Ge1-x Snx nanoparticles under non-inert conditions*

Bandgap tunable quantum dots are very interesting for a variety of electronic applications, e.g. solar cells where the tunability of the bandgap can potentially be exploited to produce high-efficiency multi-junction solar cells. One interesting candidate from the group-IV semiconductors is Ge
1-x
Sn
x
, where the bandgap is highly dependent on the Sn concentration. An increasing amount of Sn will lower the direct bandgap faster than the indirect bandgap, resulting in a direct bandgap material at approximately 8 % Sn in unstrained bulk Ge
1-x
Sn
x
[1] –[3]. Combining this property of the alloy with the quantum confinement effect, which will increase the bandgap as the nanoparticles get smaller, will potentially allow for a very specific tunability of the bandgap if the composition and size can be controlled.