Optimization of InGaN/(In,Al,Ga)N based near UV-LEDs by MQW strain balancing with in-situ wafer bow sensor

Abstract

A high resolution curvature sensor was used for in-situ monitoring of the strain state during the growth of the InGaN multiple-quantum-well (MQW) for near UV light emitting diodes (LEDs). The LED heterostructures were grown by metal-organic vapor phase epitaxy. LEDs containing different Inx Al0.16Ga0.84–x N barrier layers were compared. The results were correlated with the external quantum efficiency (EQE) and the current induced shift of the emission wavelength of the LEDs. It was found that strain-compensated or slightly compressively strained Inx Al0.16Ga0.84–x N barrier layers in the MQW, for which the net polarization in the InGaN quantum wells is close to zero, result in the highest EQE and in a stable emission wavelength independent of the drive current. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)