The effect of InGaN/GaN MQW hydrogen treatment and threading dislocation optimization on GaN LED efficiency

Abstract

We report on the effect of GaN buffer threading dislocation (TD) optimization and InGaN/GaN quantum well (QW) hydrogen ðH 2 Þ treatment on the efficiency of GaN light emitting diodes (LEDs) operating in the spectral range from 400 to 500 nm. A tenfold reduction of the TD density in the GaN buffer increased the efficiency of blue LEDs operating at high current density, while in green LEDs it had very little effect. The reduced TD density also increased the compressive strain in the InGaN QWs, and caused blue shift to the electroluminescence (EL) peak wavelength. The H 2 treatment of the QWs increased strain inside the MQW stack. It was possible to apply the H 2 treatment only to UV LEDs, as the increased strain in blue and green LEDs caused relaxation of the MQW stack. Although this resulted in smooth surface morphology of the MQW stack, it did not lead to any increase in the efficiency of the UV LEDs. r 2006 Published by Elsevier B.V.

Suppression of thermal degradation of InGaN/GaN quantum wells in green laser diode structures during the epitaxial growth

“…Several previous works reported that growth interruption 16 or introduction of H 2 after the growth of InGaN well layer 27,28 can remove In-rich InGaN clusters on the InGaN QW upper interface and enhance the thermal stability of InGaN well layer. However these approaches may blueshift the emission wavelength greatly which needs to be avoided when growing green InGaN LDs.…”

Study on Optical Properties and Internal Quantum Efficiency Measurement of GaN-based Green LEDs

“…GaN-based light emitting diodes (LEDs) have been widely studied for their great advantages in solid state lighting and display, among which blue LEDs, whose internal quantum efficiency (IQE) values can exceed 90%, have achieved great success attributed to the improvement of epitaxy growth technology and device structures [1][2][3][4][5][6][7][8]. However, the IQE values of green LEDs are still relatively low since the difficulty of growing high-quality single crystal caused by huge lattice mismatch.…”

High quality self-separated GaN crystal grown on a novel nanoporous template by HVPE

“…However, almost all of the GaN-based devices are hetero-epitaxially grown on foreign substrates due to the lack of GaN substrates for homo-epitaxy. The performances of these devices are greatly decreased because of the high threading dislocation density caused by the large lattice and thermal expansion coefficient mismatches between the foreign substrates and GaN epitaxial layer 4 .…”