Ge Films on Au(111) and Al(111): Thermal Stability

We present an analysis of Ge films grown on Au(111) and Al(111) under UHV conditions, including studies on the desorption and segregation of Ge. For desorption of a multilayer Ge/Au film, a two-step process was observed with a smooth transition in the 500-770 K range. For the case of Ge/Al a sharp desorption process takes place at ∼500 K. The final products at the surface are also different; no Ge was found after annealing the Ge/Al sample, while some Ge (of the order of 10% of ML) was found after annealing the Ge/Au sample; attributed to segregation from the bulk.