Quantum well intermixing enhancement using Ge-doped sol-gel derived Si O2 encapsulant layer in InGaAsInP laser structure

The intermixing enhancement in InGaAsInGaAsP quantum well laser structure has been investigated using the Ge-doped sol-gel derived Si O2 encapsulant layer. A band-gap shift of ~64 nm has been observed from 16% Ge-doped Si O2 capped sample at the annealing temperature of 630 °C with effective intermixing suppression using the e-beam-evaporated Si O2 layer. Ge incorporation in the sol-gel cap reduces the mismatch of thermal expansion coefficients efficiently retaining preferential vacancies, and therefore enhancing the interdiffusion rate. The intermixed material retains a good surface morphology and preserves the optical quality as evidenced by the absence of any appreciable photoluminescence linewidth broadening.