Fabrication of wavelength-shifted In0.2Ga0.8As/GaAs multiple quantum well laser diodes by impurity-free vacancy disordering at different thermal annealing temperatures

Abstract

We fabricated ridge-waveguide laser diodes with In0.2Ga0.8As/GaAs multiple quantum wells (MQWs) that have undergone impurity-free vacancy disordering (IFVD) using the SiO2 capping layer. The SiO2-capped MQW samples were annealed by rapid thermal annealing (RTA) at different temperatures. The magnitude of the blueshift estimated by the shift of photoluminescence peak energy increases with the increase of RTA temperature due to the enhanced interdiffusion of the MQWs. The electrical characteristics and lasing performance of the annealed laser diodes were compared with those of the as-grown laser diode. The operation wavelengths of 967, 946 and 927 nm with device performance comparable to that of the as-grown device were obtained in the laser diodes fabricated by the MQWs that have undergone IFVD at 850, 900 and 950 °C for 50 s, respectively. Thus, the RTA for the IFVD employed to fabricate wavelength-shifted laser diodes is believed not to seriously degrade the electrical and optical properties of the devices.