Nanoscale Heat Transport in Self -Organized Ge Clusters on Si(001)

Ultrafast time resolved transmission electron diffraction (TED) in a reflection geometry was used to study the cooling behavior of self-organized, well defined nanoscale germanium hut and dome clusters on Si(001). The clusters were heated in a pump-probe scheme by fs-laser pulses. The resulting transient temperature rise was then determined from the drop in diffraction intensity caused by the Debye-Waller effect. From a cooling time of τ =177 ps we estimated a strongly reduced heat transfer compared with homogeneous films of equivalent thickness.