Balanced Strain Compensation of InGaAs/AlGaAs/GaAsP for Improving 940 nm Infrared Light-Emitting Diodes.

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