Effect of substrate type on 200-mm diameter VCSEL performance for volume manufacturing

The availability of 200-mm diameter laser-grade GaAs substrates is limited, and therefore high cost to consumers. LED-grade substrates could be used, offering a cheaper alternative, but the effect on performance is still unknown. It’s been reported that Ge-substrates are drop-in replacements for GaAs, also with additional benefits. We report on the spatial performance of identical 940 nm VCSELs, fabricated on both LED and laser-grade GaAs, and Ge, over 200-mm. Peak wavelengths are 944.8, 944.9 and 947.0 nm for devices on LED-grade, LD-grade GaAs and Ge-substrates respectively. These results show a potential route to lower manufacturing costs per wafer.