Multiple quantum barrier structures and their application to high power visible laser diodes with strained InGaP active layers grown by MOCVD

Abstract

We introduced a multiple quantum barrier (MQB) which was grown by MOCVD between the active layer and p-cladding layer to enhance potential barrier height. The MOCVD system was improved to realize the growth of MQB structures for the first time. We compared threshold current densities ( J th) of various barrier/well thickness combinations in order to optimize the MQB structure. We found that the thickness of barriers and wells should be 1.7 and 1.15 nm, respectively, to minimize J th. The optimized MQB significantly reduced the J th of visible laser diodes. Strained active layers with compressive stress were employed as another approach for the improvement of the threshold current. We found that the strained active layer is as effective as the MQB in reducing J th. The lowest J th has been achieved by the combination of MQBs and strained active layers. We realized an output power of 40 mW, at 90°C, at a lasing wavelength of 675 nm. to our knowledge, these are the best data.