Effect of Sb composition on lateral oxidation rates in AlAs1-xSbx

We demonstrate the effect of antimony (Sb) composition on the oxidation mec hanism of AlAs1-xSbx (x < 0.21) layers on GaAs substrates. It has been demo nstrated that addition of a group-III element like Ga to AlAs slows the rat e of oxidation. In contrast, addition of a group-V element like Sb to AlAs changes the oxidation mechanism in more than one way. The oxidation rate in creases with Sb addition, and the oxidation reaction changes from a diffusi on-limited mechanism to a reaction-rate-limited mechanism at higher oxidati on temperatures. This is attributed to the increase in the permeability of the oxide. Nonuniform segregation of Sb is observed upon oxidation. The act ivation energy of the oxidation reaction-rate constant initially decreases with the Sb composition upto 10%, further Sb addition increases the activat ion energy. (C) 2000 American Institute of Physics. [S0003-6951(00)00410-1] .