Probing the Internal Electric Field in GaN/AlGaN Nanowire Heterostructures

We demonstrate the direct analysis of polarization-induced internal electric fields in single GaN/Al0.3Ga0.7N nanodiscs embedded in GaN/AlN nanowire heterostructures. Superposition of an external electric field with different polarity results in compensation or enhancement of the quantum-confined Stark effect in the nanodiscs. By field-dependent analysis of the low temperature photoluminescence energy and intensity, we prove the [0001]-polarity of the nanowires and determine the internal electric field strength to 1.5 MV/cm.