Balanced Strain Compensation of In_0.07GaAs/Al_0.2GaAs/GaAsP_0.06 for Improving 940 nm Infrared Light-Emitting Diodes

Optimum strain compensation structures for In_0.07GaAs-based MQWs were investigated to obtain a higher output power for infrared lighting-emitting diodes (IR-LEDs) requiring a 940 nm wave-length. A GaAsP_0.06 tensile strain material for compensating the compressive strain of In_0.07GaAs quantum wells was used as a quantum barrier. To improve upon the excessive unbalance strain condition caused due to the In_0.07GaAs quantum well and GaAsP_0.06 quantum barrier, a conditioned Al_0.2GaAs strain balancing barrier was also investigated. Through subsequent photoluminescence (PL) measurements, it was found that the GaAsP_0.06 tensile strain barrier could effectively compensate for the compressive strain of In_0.07GaAs quantum wells. Furthermore, the PL intensity of In_0.07GaAs/GaAsP_0.06 MQWs was observed to be markedly improved by using an Al_0.2GaAs strain balancing barrier. A fabricated IR-LED chip, having In_0.07GaAs/GaAsP_0.06 MQWs with an Al_0.2GaAs strain balancing barrier, showed a 60% higher light output power than conventional MQWs. These results subsequently suggest that using GaAsP_0.06 and Al_0.2GaAs barriers effectively improved unbalanced strain conditions of lattice-mismatched In_0.07GaAs based MQWs requiring a 940 nm emitting wavelength.