Localization and defects in axial (In,Ga)N/GaN nanowire heterostructures investigated by spatially-resolved luminescence spectroscopy

TL;DR

This study uses spatially-resolved luminescence spectroscopy to investigate the localization and defects in (In,Ga)N/GaN nanowire heterostructures, revealing compositional variations and defect contributions affecting their emission properties.

Contribution

It provides detailed spatial analysis of emission mechanisms, compositional pulling effects, and defect contributions in (In,Ga)N/GaN nanowire heterostructures for the first time.

Findings

Emission energy shifts along nanowire insertions due to compositional pulling

Carrier localization at potential fluctuations influences luminescence

Structural and point defects contribute to emission characteristics

Abstract

(In,Ga)N insertions embedded in self-assembled GaN nanowires are of current interest for applications in solid state light emitters. Such structures exhibit a notoriously broad emission band. We use cathodoluminescence spectral imaging in a scanning electron microscope and micro-photoluminescence spectroscopy on single nanowires to learn more about the mechanisms underlying this emission. We observe a shift of the emission energy along the stack of six insertions within single nanowires that may be explained by compositional pulling. Our results also corroborate reports that the localization of carriers at potential fluctuations within the insertions plays a crucial role for the luminescence of these nanowire based emitters. Furthermore, we resolve contributions from both structural and point defects in our measurements.