Structure, Process And Measurement Of Ohmic Contact For MBE GaAs Quantum Cascade Laser

MBE GaAs-based Quantum Cascade Laser is a stable lasing source which has series of quantum well on the GaAs surface to utilize resonant optical by quantum cascade effect. Thicknesses of those quantum wells are nanometer to even monolayer. Impurity has great impact on the luminous efficacy.For current AuGeNi ohmic contact system on GaAs material, the metal Ni has great diffusion in the active region, it degrade the quantum cascade effect.Laser is high-power device which generates a large number of energy. It needs cooling systems such as gas liquid that could degrade its practicability. Ohmic contact is a key component for device connecting and has strong impact on the output efficiency.After the annealing process which is normally used in ohmic contact processes, there is non smoothing surface on the top metal. It is very bad for laser device which is optical sensitive,For the problems above, this dissertation discusses and researches on:1,Acquiring parameters for the process of ohmic contact on n-GaAs,2,Improving the measurement configuration for ohmic contact resistivity,3,Introducing Ge/Au/Ag/Au configuration to avoid Ni negative impact on quantum cascade laser device,4,Introducing LTG GaAs configuration to avoid annealing negative impact on quantum cascade laser device,5,Introducing diffusion barrier (Pd) to improve the surface morphology.