Benefits and limitations in barrier design in InAsP/GaInP strain-balanced MQWs for improving the 1.3 /spl mu/m waveguide modulator performance

We have investigated the limitations in the barrier design for InAsP/GaInP strain-balanced multiple quantum wells (MQWs) by measuring double-crystal X-ray rocking curves and room-temperature photoluminescence. We show that in thin-barrier (/spl sim/70 /spl Aring/) structures with 8 MQWs, zero net strain can not be achieved due to the relaxation of the GaInP barriers caused by higher tensile strain. The net strain has to be designed at the compressive side and within the range of -0.26% to -0.54% to obtain high structural stability. Photocurrent spectra show that with 70 /spl Aring/-thick barriers, the MQW region is 35% more absorptive than with 115 /spl Aring/-thick barriers.