Strain relaxation in InGaAs lattice engineered substrates

Strain relaxation of hypercritical thickness InxGa1-xAs layers has been obs erved during lateral oxidation of underlying AlAs layers. Strain relaxation of InxGa1-xAs layers was studied as a function of indium composition and t he AlAs oxidation temperature. It is proposed that the enhanced strain rela xation is due to two factors. The first is enhanced motion of threading dis locations due to stresses generated during the lateral oxidation process. T he second is the porous nature of the InxGa1-xAs/A(2)O(3) inter face that m inimizes the interaction of threading dislocations with existing misfit dis location segments. The extent of strain relaxation increases with increasin g oxidation temperature, whereas the efficiency of strain relaxation was fo und to decrease with increasing indium composition. The efficiency of strai n relaxation upon oxidation can be improved by reducing the misfit dislocat ion density at the InxGa1-x/AlAs interface prior to oxidation and by changi ng the nature of the InxGa1-xAs/Al2O3 interface.