Red-shift in the InGaAsP/GaInP active region using impurity free vacancy diffusion induced quantum well intermixing

Red-shift in 808 nm Al-free InGaAsP/GaInP active region using impurity free vacancy diffusion (IFVD) induced quantum well intermixing (QWI) was firstly reported in this paper. The laser diode wafer had an active region of single 12 nm InGaAsP quantum well and two 20 nm GaInP barriers and then 200 nm SiO2 dielectric film was deposited on the surface of the wafer by magnetron sputtering. The QWI processes were induced by rapid thermal annealing (RTA) at different times and temperatures, respectively. Red-shift instead of blue-shift in the InGaAsP/GaInP active region was found increased with the increasing annealing time and annealing temperature, and the largest red-shift of 7.3 nm was obtained in the sample annealed at 750 °C for 210 s. The results were analyzed theoretically and experimentally by Ga distribution simulation and X-ray photoelectron spectroscopy (XPS) to testify the theory of QWI.