Focused ion-beam implantation induced thermal quantum-well intermixing for monolithic optoelectronic device integration

By focused ion beam implantation induced thermal intermixing the bandgap of quantum-well layer structures can be selectively changed. This allows lateral bandgap engineering and gives a new degree of freedom for lateral structuring. The principle technological aspects like the dependence of the bandgap shift on implantation parameters and the spatial resolution are investigated and applied to the fabrication of photonic and optoelectronic devices. Lateral waveguiding in InP-based materials, the possibility of monolithic integration of bandgap shifted waveguide areas into active devices and the improvement of the lateral carrier confinement in ridge waveguide lasers are demonstrated. Due to the high spatial resolution, modulated bandgap gratings could be realized with periods down to 90 mn. These bandgap gratings were used to create gain-coupled distributed-feedback lasers in different material systems with well controlled single-mode emission