Impurity free vacancy diffusion induced quantum well intermixing based on hafnium dioxide films

Impurity free vacancy diffusion (IFVD) induced quantum well intermixing (QWI) based on electron beam evaporation hafnium dioxide (HfO2) in the red light diode laser wafer is firstly demonstrated in this work. The red light diode laser wafer had an active region of two 6 nm-thick GaInP quantum wells and three 8 nm-thick AlGaInP quantum barriers. 135 nm thick HfO2 film was evaporated on the surface of the diode laser wafer at 200 °C. The QWI processes were induced by rapid thermal annealing (RTA) for 20 s at different temperatures. The intensity and the full width at half maximum (FWHM) of the active region emitting wavelength were found increasing and decreasing with the increasing annealing temperature, respectively. When the sample was annealed at 1000 °C, a blue shift of 18 nm was found by the HfO2 IFVD induced QWI. Moreover, the diffusion lengths and inter-diffusion coefficients were calculated based on concentration distribution in the active region, and the inter-diffusion coefficient values were higher than the results in the Zn impurity diffusion induced QWI.