Abstract: | In the temperature range from 950 to 1200 K Kp-values result from 5 · 10−5 to 6,9 · 10−3 for the heterogeneous reversible reaction Ge(s) + H2O(g) ⇋ GeO(g) + H2O(g), the average reaction enthalpy being 46,5 ± 05 kcal/mol. Etching rates calculated with these equilibrium constants for closed systems are 20-25% larger than the experimental etching rates for (110)-Ge in the sandwich device. The ratio of the etching rates is for (111)-, (100)- and (110)-Ge 1:1,4:1,8; the average reaction enthalpy calculated experimentally is 46 ± 1 kcal/mol for the temperature range 1000-1200 K. The dependence of transport rate on distance between source and substrate characterizes the sandwich device as a quasi-closed system with the diffusion as the rate controlling step of the material transport. |