Design of Schottky barrier for plasmon-induced hot-electron passivation of defect environments of semiconductor quantum dots

Abstract

Metal oxide plasmonic metafilms consisting of a Au/Si Schottky barrier in close vicinity of a Si/Al oxide charge barrier can suppress defect-induced non-radiative decay rates of semiconductor quantum dots, enhancing their emission efficiency beyond what the near field enhancement of metallic nanostructures (Purcell effect) can offer (Sadeghi et al 2017 Nanotechnology 29 015402). In this paper we study the impact of the efficiency of the hot electron transfer across the Schottky barrier on such plasmon-induced suppression of the impact of the defect environments. For this the emission intensity and dynamics of quantum dots on such metafilms are studied as the structural features of the Schottky barrier are controlled. We consider the Si layer that separates the Schottky barrier from the charge barrier is either intrinsically undoped, p-doped, or n-doped. Our results show the metafilms with n-type Si can elongate the emission lifetime of the quantum dots the most, suggesting a superior quarantine of excitons against the defect environments. This highlights the fact that n-type Schottky barriers can more efficiently capture the hot electrons generated via non-radiative decay of plasmons. This allows an improved plasmon-induced screening of the excitons against the defect environment.