Quantum well intermixing of In1-xGaxAs/InP and In1-xGaxAs/InP and In1-xGaxAs/In1-xGaxAs1-yPy multiple-quantum-well structures by using the impurity-free vacancy diffusion technique

We investigated the influence of strain and barrier composition on the quan tum well intermixing (QWI) in In1-xGaxAs/In1-xGaxAs1-yPy multiple-quantum-w ell (MQW) structures by using the impurity-free vacancy diffusion technique . A compressively strained MQW structure showed a higher degree of intermix ing than a lattice-matched one due to lower thermal stability and larger ba ndgap difference between the quantum well (QW) and the barrier. Also, the p hotoluminescence blueshift increases with increasing difference of bandgap energy between the QW and the barrier. In addition, a highly selective QWI with a large bandgap shift difference of 123 meV (195 nm) using an identica l silica cap has been achieved from samples capped with InGaAs/SiO2 and InP /SiO2 capping layers. This behaviour may be attributed to the difference in thermal expansion coefficient between InGaAs and InP at the annealing temp erature.