Power Dependence of Photoluminescence Emission in Partial VCSEL on Bulk GaAs and Ge Substrates

Partial vertical cavity surface emitting laser (VCSEL) structures, AlGaAs-based distributed Bragg reflector (DBR) with InGaAs/ GaAsP multi-quantum wells (MQWs), grown on Ge substrates were investigated and compared to conventional GaAs substrates. While both substrates demonstrated successful epitaxy, the Ge-based samples showed distinct differences in power-law behavior (β=1.03 vs. 1.34) and broader FWHM (34-44% increase), indicating higher defect densities. Despite these challenges, results confirm Ge's viability as a cost-effective, scalable substrate for AlGaAs-based VCSELs.