The Study For The Accelerated Degradation Test Method And Facet Coating Reliability Of High Power GaAs-based Laser Diodes

High power semiconductor laser diodes have many advantages such as high power conversion efficiencies, long duration life and high reliability, which are widely used in the fields of solid-state pumping, materials processing, optical communications. Recently, as the output power of laser diodes increases, the application width becomes more and more larger. Thereby, the reliability become a main issue. In this thesis, we performed mainly the accelerated aging experiment and reliability study of high power GaAs-based 808 nm laser diodes. Due to high optical power density, catastrophic optical damage(COD) usually happened in the output facet. Thus, several failure analysis methods have been used to study the failure mode, degradation mechanism of the facet coating.The research work includes a few aspects as follows:1?The accelerated aging experiment of 3.5W 808 nm laser diodes was carried out under constant current and temperature are carried out under the case temperature of 30?, 45?,60?,respectively. The sensitive parameter of optical power is monitored off-line. For optoelectronic devices, optical power is reduced with the heat power increase, which lead to the junction temperature rises and then the optical power reduces. This process forms a positive feedback. In the process of lifetime extrapolation, in order to avoid the error induced by change of junction temperature, the degradation rate is obtained from the data of 5% decrease on the optical power and is determined by the junction temperature, working current and activation energy. The junction temperature rise originating from the 5% decrease on the optical power is little and can be neglected. The failure criterion is the 20% decrease on the optical power. The lifetime can be obtained by degradation rate extrapolating the time when the optical power decreases by 20%. Combined the Weibull distribution and Arrhenius model, the lifetime on the room temperature can be extrapolated. In this experiment, the activate energy is 0.62 eV, and the lifetime on the room temperature is 9792 hours.2?With the output power increase, the facet coating suffer high power density and temperature, thus the reliability of facet coating attract more and more attention. The GaAs-based high power laser diodes in the paper take the high refractive index, silicon and the low refractive index, sapphire as the facet coating. The failure analysis techniques such as focused ion beam(FIB),high resolution transmission electron microscopy(HRTEM)and energy dispersive x-ray spectrometer(EDS) were used to investigate the facet coating of laser diodes. The results showed that the silicon layer near the active region of the aged sample appeared the oxidation and the silicon diffusion, while the area outside the active region of the aged sample and the two areas of the fresh sample didn't appear the oxidation and diffusion. After long-time radiation, the silicon layer appeared diffusion and oxidation and degradation. In the process of diffusion and oxidation, the electron-hole pair recombined non-radiatively, and the temperature rise, which further promote the silicon diffusion and oxidation and form a loop. When the temperature reached the melting point of material, the catastrophic optical damage(COD) appear.3?In this section, the temperature rise and reverse leakage current of high power laser diodes were analyzed. The longitudinal heat conduct process was investigated by the electrical method. The electrical, optical, thermal parameters and their relations were analyzed. The componential thermal resistance was analyzed by structural function method. The package thermal resistance dominates the total thermal resistance and decrease with the power increase. Compared with the fresh sample, the apparent thermal resistance of the aged sample increase, especially the chip thermal resistance. The facet temperature distribution was investigated by the infrared method. The temperature near the active region is higher than that outside the active region, which lead to the silicon diffusion and oxidation near the active region. The temperature near the active region of the aged sample rise 42?, while that of the fresh sample rise 31?. The reverse leakage current was investigated by EMMI. The leakage current of the aged sample is little, while the leakage current of the aged sample increase and the photo in the active region was observed.