Impact of distributed Bragg reflector on carrier and photon dynamics in GaN-based surface emitting diodes manifested by ultrafast transient absorption spectroscopy

Abstract

Small signal modulation bandwidth characterized by relaxation oscillations (ROs) of GaN-based vertical cavity surface emitting laser diodes are of great importance in high-speed applications. In this work, we investigate the impact of distributed Bragg reflectors (DBRs) on ROs by developing a simulation framework, which can accommodate the reflected photons self-consistently in the rate equation model. Carrier and photon dynamics in the active region and at the transmitting end have been evaluated for a typical GaN/InGaN multiple quantum well heterostructure having a dielectric DBR. Temporal broadening in photon dynamics is observed due to the phase difference. Interestingly, an enhanced radiative recombination rate is also noticed due to the increased confinement, which leads to a reduced turn-on delay. Transient absorption spectroscopy has been performed to obtain the decay rates of captured carriers in the well and it turns out be in harmony with the simulation results. Photoluminescence spectroscopy also validates the increased radiative recombination. © 2019 The Japan Society of Applied Physics ( ) ( )where N b and N w are the carrier densities in the barrier and well regions, respectively, and N p is the photon density inside

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Carrier-Induced Defect Saturation in Green InGaN LEDs: A Potential Phenomenon to Enhance Efficiency at Higher Wavelength Regime

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