Improved performance characteristics of violet InGaN MQW LDs through asymmetric W-shaped quantum wells

Abstract

Abstract This study focuses on the numerical study of the built-in electric field effects, induced by spontaneous and piezoelectric polarization, on the performance characteristics of violet InGaN MQW LDs. The simulation results indicate that the induced electric field significantly deteriorates LDs performance due to QCSE, band bending, and consequent separation of the electron and hole wave functions. A new asymmetric W-shaped QWs structure is proposed to overcome QCSE, and enhance the overlapping of electron and hole wave function, and to improve the band bending situation. The In0.16Ga0.84N/InyGa1-yN/In0.16Ga0.84N QWs LDs improve the overlapping of electron and hole wave functions from 52.52, 26.39, and 4.47% for QW1, QW2, and QW3 of conventional LD structure to 48.33, 48.12, and 53.12%, respectively. Improved distributions of the electron and hole carriers in the active region, along with a higher electron and hole overlapping, result in enhanced radiative and stimulated recombination rates, hence, higher output power, and lower threshold current. The proposed W-shaped QW LDs improves threshold current and output power from 82.87 mA to 15.89 mW to 60.67 mA and 20.69 mW, respectively.