MISFIT STRESS-INDUCED COMPOSITIONAL INSTABILITY IN HETEROEPITAXIAL COMPOUND SEMICONDUCTOR STRUCTURES

We have calculated the effect of misfit stress on the compositional st ability of strained-layer hetero-epitaxial compound semiconductor stru ctures. For uniformly stressed layers, a simple formula is derived for the change in chemical potential of the lattice atoms diffusing acros s the hetero-interface. An increase in the total chemical potential in dicates that interdiffusion of the specific elements is thermodynamica lly unfavorable and therefore the composition of the structure is stab le with respect to the misfit stress-induced interdiffusion of the spe cific elements. On the other hand, a decrease in the total chemical po tential indicates that the interdiffusion will be driven by the misfit stress and the composition of the heterostructure is unstable. Variou s strain-layer systems of III-V compound semiconductors such as In1-xG axAsyP1-y/InP, In1-xGaxAsyP1-y/GaAs, (Al1-xGax)(y)In1-yP/GaAs, (Al1-xG ax)(y)In1-yAs/GaAs, In1-xGaxP/GaAs, In1-xGaxSb/InP, etc., are examined and their stability is discussed. (C) 1996 American Institute of Phys ics.