Island growth and phase separation in strained InAs/sub 1-x/P/sub x//InP heterostructures

Using x-ray diffraction and transmission electron microscopy we have found that InAs/sub 1-x/P/sub x/ films deposited on InP(001) substrates with organometallic vapor phase epitaxy grow in an unusual phase-separated island growth mode related to strain. Initially, pseudomorphic islands of intermediate composition form and grow only until some point in the relaxation process, possibly a critical value of the strain, after which islands of the intended composition begin to appear. Furthermore, both types of islands are found to penetrate deeply into the substrate.