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problem about CVD and alloys Suppose you have to deposit a mixed layer with a ce

ID: 1415905 • Letter: P

Question

problem about CVD and alloys

Suppose you have to deposit a mixed layer with a certain composition, say SiGe, with an equal amount of Si and Ge. The activation energy, and thus the corresponding Arrhenius rate coefficients are different. For simplicity, assume that the diffusion coefficient and the constant ks0 in the Arrhenius rate for each precursor is the same.

a) Sketch the behaviour of the deposition rate for each element.

b) Which regime offers the best possibilities to deposit the required layer.

Explanation / Answer

a)   the deposition rate for each element is an increasing parabolic curve , which become constant after a particular saturation time .

b)   The LBL deposition method allows to deposit PEM films on almost all kinds of surfaces irrespective of its chemical composition and surface charge: only the thickness of the first few deposited layers is dependent on the used substrate.