Spaepen

Stress-thickness as a function of film thickness of amorphous alumina.

Spaepen has used an ultra-sensitive laser deflection technique to make in situ measurements of the stress evolution during electron beam deposition of amorphous alumina. He has combined these measurements with density and adsorption porosimetry measurements to determine the microstructure of the resultant thin films. He successfully explored the dependence of the stiffness, as determined by the biaxial modulus, of the films on the microstructure. These measurements provide important guidance in determining the conditions for optimum growth of these films.