ETCH RATE AND DETERIORATION OF MAGNESIUM ALUMINUM SPINEL IN HYDROGEN

In this paper the rate of material removal in hydrogen of stoichiometric spinel is presented as a function of crystallographic orientation, time, and temperature. For example, at 1000 degree C the rate is similar 1 A/min; at 1300 degree C, similar 100 A/min. However, it was found that sucha hydrogen ambient promotes crazing of the substrate surface, thus degrading its suitability for heteroepitaxy. This phenomenon was studied, and it is suggested that the cause is due to a preferential out-diffusion of magnesium from the surface, which induces a strain large enough to result in brittle fracture. It has been shown that the crazing is obviated by the use of helium as a carrier gas.