Quantum well intermixing enhancement using Ge-doped sol-gel derived SiO2 encapsulant layer in InGaAs∕InP laser structure

Abstract

The intermixing enhancement in InGaAs∕InGaAsP quantum well laser structure has been investigated using the Ge-doped sol-gel derived SiO2 encapsulant layer. A band-gap shift of ∼64nm has been observed from 16% Ge-doped SiO2 capped sample at the annealing temperature of 630°C with effective intermixing suppression using the e-beam-evaporated SiO2 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.