or not samples 1 and 2 were annealed with germanium facing down to the silicon surface and no cavities were detected sample 3 was annealed with germanium surface facing up to the argon ambient atmosphere and severe cavity formation was detected this is shown in fig2 and 3 a coating was detected on the rta annealing chamber after the cyclic annealing experiments the cavities in the germanium surface may have been caused by u201c thermal etching u201d or evaporation from the germanium surfaces when the germanium surface was placed against the silicon wafer the thermal etching was less serious in order to confirm this explanation a layer of teos was deposited on samples 4 5 6 and 7 before cyclic annealing the cyclic annealing results were consistent with the u201c thermal etching u201d theory fig4 depicts sample 5 at cyclic annealing temperatures of 900 u00b0 c for five minutes and at 780 u00b0 c for five minutes no cavities were detected although the annealing temperature was relatively high therefore the teos layer prevented the evaporation of germanium film during cyclic annealing at higher temperatures as shown in fig5 a different feature was observed this appears to be due to melting and recrystallization of germanium film the temperature was measured by thermocouple in contact with sample surface although the actual temperature of the film may be slightly higher than 920 u00b0 c which is very close to the germanium.