Potential and limitations of selective disordering processes in GaInAsP and AlGaInP heterostructures

The paper reviews different approaches to selective intermixing of GaInAs/InP- and GaInP/AlGaInP-quantum wells. These techniques are based on the fact that quantum wells involve extremely large concentration gradients at the heterointerfaces. These metastable structures give rise to strong interdiffusion effects in high temperature processes. Due to the diffusion of atoms from the quantum well barriers into the quantum well layers and the simultaneous diffusion of atoms out of the active layer the interdiffusion results generally in an increase of the band gap in the quantum well layers. By implantation damage or dopant diffusion the intermixing of the quantum wells may be enhanced locally. Therefore this technique can be used to define e.g. buried waveguides without the need of multiple epitaxy steps. We have investigated intermixing processes in GaInAs/InP- and GaInP/AlGaInP-quantum wells by using rapid thermal annealing. A selective intermixing was obtained by ion implantation in masked samples and by a local modulation of the thermal stability in suitably etched structures