Graphene induced weak carrier localization in InGaN nanorods directly grown on graphene-covered Si

Abstract

In this paper, we propose an investigation on the graphene monolayer effect, elaborated on Silicon (Si) by atmospheric-pressure chemical vapor deposition (APCVD), on the carrier localization in ternary InGaN nanorods (NRs) grown by metal-organic chemical vapor deposition (MOCVD). The growth has been proved using scanning electron microscopy (SEM) and Raman technic. SEM investigations support NRs size fluctuations and the presence of random coalescence zones. Raman study reveals the graphene self-doping and low tensile strain which constitutes an origin of the random potential fluctuation. The temperature dependent photoluminescence (PL) of InGaN NRs showed the presence of the localization phenomenon due, principally, to the NRs density and size inhomogeneity and composition fluctuations. Carrier localization increases Auger recombination rates more than radiative rates and is therefore detrimental to the internal quantum efficiency (IQE) of nitrides-based emitters. Our work suggests a partial suppression of the phenomenon effects through a partial suppression of random potential fluctuations by the mean of the direct growth of nitride on Graphene-covered Si substrate. Our qualitative investigations show a reduction of the localization effects due the added graphene monolayer which is quantitatively reinterpreted using the Localized State Ensemble model (LSE) for the first time. Our findings are substantial to advance the integration of nitrides-based devices on any substrates of choice, thereby permitting novel designs of nitrides-based heterojunction device concepts.