Photoemission Study on Si and Ge Segregation on Al/Si_0.8Ge_0.2 Structures

We have demonstrated the formation of an ultrathin Si and Ge layer on an Al/Si 0.8 Ge 0.2 (111) structure caused by controlling the annealing condition. From the XPS characteristics, the annealing temperature, rather than the time, was found to be important in controlling the Si and Ge segregation. Also, by thermal annealing in N 2 ambient, the segregated Ge on the Al/Si 0.8 Ge 0.2 structure was found to be stable and resistant to oxidation due to the surface Al oxide layer and the segregated Si. We also found that Ge atoms were highly selectively segregated from the Al/Si 0.8 Ge 0.2 (111) structure below 500ºC. It was also found that Ge atoms could be selectively segregated from the Al/Si 0.8 Ge 0.2 (111) structure by rapid thermal annealing. The results will lead to the development of two-dimensional Ge crystals that are highly compatible with Si ultra-large-scale integration processing.