Quantum well intermixing of In_1-xGa_xAs/InP and In_1-xGa_xAS/In_1-xGa_xAs_1-yP_y multiple-quantum-well structures by using the impurity-free vacancy diffusion technique

摘要

We investigated the influence of strain and barrier composition on the quantum well intermixing (QWI) in In_1-xGa_xAs/In_1-xGa_xAs_1-yP_y multiple-quantum-well (MQW) structures by using the impurity-free vacancy diffusion technique. A compressively strained MQW structure showed a higher degree of intermixing than a lattice-matched one due to lower thermal stability and larger bandgap difference between the quantum well (QW) and the barrier. Also, the photoluminescence 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 identical silica cap has been achieved from samples capped with InGaAs/SiO_2 and InP/SiO_2 capping layers. This behaviour may be attributed to the difference in thermal expansion coefficient between InGaAs and lnP at the annealing temperature.