Effect of barrier thickness on the carrier distribution in asymmetric multiple-quantum-well InGaAsP lasers

Four asymmetric multiple-quantum-well (AMQW) laser structures have been grown and tested. The structures were designed to study the effect of the thickness of the barriers on the distribution of carriers amongst the quantum wells by comparing the transition cavity lengths (TCL) of mirror image AMQW lasers, The TCL method provides a quantitative measure of the degree to which the uneven carrier distribution affects the net gain of wells owing to the position of the well in the active region. We experimentally demonstrate that reducing the thickness of the barrier layers from 100 to 50 Angstrom results in a significantly more uniform carrier distribution. The thickness of the barriers is thus shown to be an important design parameter for MQW lasers.