Investigation on Polarization Induced Electro-Optical Property of GaN LED Using TEM-EBIC Combined with Cathodoluminescence

Strained InGaN layers grown on a c-plane sapphire is known to have strong spontaneous and piezoelectric polarization field, where the discontinuity of polarization at heterojunction is to induce bounded surface charges [1]. This polarization-related phenomenon can affect the internal electric field of active region and induce the quantum-confined stark effect (QCSE) at quantum well. QCSE results in the spatial separation of electrons and holes in the quantum well, blue shift, and increase of carrier density [2]. To reduce the polarization induced QCSE, efforts were made by growing GaN-InGaN on semi-polar and non-polar substrates [3]. In this study, we report the polarization induced electro-optical property of polar, semi-polar, and non-polar GaN-InGaN LED in nano-scale.