SURFACE-ENERGY MODEL FOR THE THICKNESS DEPENDENCE OF THE LATERAL OXIDATION OF ALAS

The lateral oxidation rate of AlAs layers decreases dramatically for l ayers thinner than about 500 Angstrom, because the activation energies for the rate constant of the reaction at the oxidation front increase s by an amount inversely proportional to the layer thickness. We deriv e a model for the thickness dependence of the lateral oxidation rate o f AlAs based on the surface energy of the curvature observed at the ox ide tip. From the model, we show that the linear oxidation rate has an exp(-theta(0)/theta) dependence on the AlAs layer thickness theta, an d we can predict the slowing of oxidation when the AlAs layer is cladd ed with AlGaAs barriers. Also, we estimate the surface energy of the A lAs/oxide interface to be 50 eV/nm(2). (C) 1997 American Institute of Physics.