The etching of GaAs and AlxGa1-xAs have been characterized in (NH4)2Sx solution with various excess sulfur concentrations and for temperatures ranging from 20 to 60°C. The etch rate varies with the concentration of excess sulfur and is highest at 60°C using a 4% excess sulfur solution. The etch rate of Al xGa1-xAs increases exponentially with increasing Al mole fraction. Activation energies of 19.8 and 15.9 kcal/mole are obtained for GaAs and Al0.3Ga0.7As in 4% (NH 4)2Sx, respectively. These high values and the linear time dependence of etch rates signify that the etching process of Al xGa1-xAs in (NH4)2S x solutions is predominantly reaction-rate limited. Possible chemical processes involved in the etching and the formation of a passivating sulfur layer are discussed.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)