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Effect of Quantum Barrier Thickness in the Multiple-Quantum-Well Active Region of GaInN/GaN Light-Emitting Diodes

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8 Author(s)
Guan-Bo Lin ; Dept. of Electr., Comput., & Syst., Eng., Rensselaer Polytech. Inst., Troy, NY, USA ; Dong-Yeong Kim ; Qifeng Shan ; Jaehee Cho
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The dependence of the polarization-induced electric field in GaInN/GaN multiple-quantum-well light-emitting diodes (LEDs) on the GaN quantum barrier (QB) thickness is investigated. Electrostatic arguments and simulations predict that a thin QB thickness reduces the electric field in the quantum wells (QWs) and also improves the LED efficiency. We experimentally demonstrate that the QW electric field decreases with decreasing QB thickness. The lower electric field results in a better overlap of electron and hole wave functions and better carrier confinement in the QWs. A reduced efficiency droop and enhanced internal quantum efficiency is demonstrated for GaInN/GaN LEDs when the QB thickness is reduced from 24.5 to 9.1 nm.

Calculated conduction-band energy of a GaInN/GaN MQW structure with a 3 nm thick QW and with 4 nm, 8 nm, and 16 nm thick QBs. With decreasing the QB thickness, the internal electric field in the QW becomes smaller (smaller slope of E_{rm c} in the magnified lower circle), causing a smaller potential difference across the QW (the upper circle). Calculated conduction-band energy of a GaInN/GaN MQW structure with a 3 nm thick QW and with 4 nm, 8 nm, and 16 nm thick QBs. With decreasing the QB thickness, the internal electric field in the QW becomes smaller (smaller slope of E_{rm c} in the magnified lower circle), causing a smaller potential difference across the QW (the upper circle).

Published in:

Photonics Journal, IEEE  (Volume:5 ,  Issue: 4 )