Determination of the effect of a strain relaxation layer on the internal electric field measurement in an InGaN/GaN multiple-quantum-well structure by using electroreflectance spectroscopy

Abstract

We investigate the effect of a strain relaxation layer (SRL) on the internal-field measurement of InGaN/GaN multiple quantum wells (MQWs) in blue light-emitting diodes by using electroreflectance (ER) spectroscopy. The polarization charges of the SRL are relatively smaller than those of the MQWs because the SRL has a lower indium composition in the InGaN/GaN superlattice. Therefore, the phases of the ER signals from the MQWs and the SRL are reversed at different bias voltages. From two different compensation voltages, the piezoelectric fields in MQWs and the SRL are estimated separately. When the SRL is not considered, the piezoelectric field in the MQWs can be underestimated.