Lateral oxidation kinetics of AlAsSb and related alloys lattice matched toInP

The lateral oxidation kinetics of AlAs0.56Sb0.44 on InP substrates have bee n investigated to understand the antimony segregation process during oxidat ion. Oxidation layers were grown between GaAsSb buffer and cap layers on In P substrates by molecular beam epitaxy. Oxidation temperatures between 325 and 500 degreesC were investigated for AlAsSb layer thicknesses between 100 and 2000 Angstrom. At low oxidation temperatures (T-ox less than or equal to 400 degreesC), the process is reaction limited with a linear dependence of oxidation depth on time. At intermediate oxidation temperatures (400 < T -ox < 450 degreesC), the oxidation process becomes diffusion limited. At hi gh oxidation temperatures, the oxidation process is termed self-limiting si nce at 500 degreesC the process stops entirely after oxidation times on the order of 5 min and distances of 40 mum. It is shown that the antimony floa t layer lags the oxidation front by a temperature-dependent distance, which suggests that the antimony may change the structure of the oxide at the fr ont and cause self-limiting behavior. The oxidation kinetics of AlxGa1-xAsS b and AlxIn1-xAsSb have also been investigated. Antimony segregation is not suppressed during oxidation of Ga-containing layers and AlInAsSb quaternar y alloys do not oxidize laterally at measurable rates in the range 400-525 degreesC. SiNx cap layers deposited after growth and before oxidation do no t affect the Sb segregation or oxidation rate, but do smooth the cap surfac e by preventing uneven Sb metal segregation to the cap/oxide interface. (C) 2001 American Institute of Physics.