Effects of quantum well thickness and aluminum content of electron blocking layer on InGaN-based laser diodes

Abstract

The effects of quantum well (QW) thickness and aluminum content of electron blocking layer (EBL) on device performance of InGaN-based laser diodes (LDs) are numerically investigated with LASTIP. It is found that the device performance of the 3.0-nm-thick QW LD is the best. The threshold current increases and the output power at 120 mA decreases when the QW thickness is too thin or too thick. Actually, the optical and electrical characteristics of InGaN-based LDs demonstrate that the optical confinement factor decreases and optical loss increases when the QW thickness is too thin. The stimulated recombination rate decreases due to the poorer overlap of electron–hole wave functions and the enhanced polarization-induced built-in electric field when the well thickness is too thick. Moreover, the calculation results of LDs with different aluminum compositions of EBL demonstrate that the effectiveness of EBL would be enhanced through increasing aluminum content when the thickness of QWs decreases, because there is a reduction of ground-state energy level and the energy difference between the ground state and the top of the quantum barrier.