Joshua Letton

Date of Award

Summer 2020

Document Type

Open Access Thesis


Electrical Engineering

First Advisor

MVS Chandrashekhar


The work that follows examines the impact of lead sulfide quantum dots on a native epitaxial graphene (EG) SiC Schottky device, resulting in a hybrid optoelectronic device which presents a possible avenue towards a novel hybrid carbide-based Schottky solar cell. The active (n-type SiC) and contact (graphene) layers for the Schottky junction of the device were grown epitaxially using a novel technique incorporating tetrafluorosilane (TFS) as a precursor gas. The bare EG/SiC device was characterized based on its I-V behavior in dark and under illumination for both forward and reverse bias conditions. The initial characterization demonstrated the expected Schottky diode rectifying behavior and an action spectra consistent with absorption at and above the bandgap of 4h-SiC (3.23 eV, 380 nm). After initial characterization, PbS QDs synthesized as described by Zhang et al.[63] and treated with an ethanedithiol (EDT) ligand exchange[29] were incorporated with the Schottky device. The hybrid device demonstrated significant changes in I-V behavior and the observed action spectra. There was an increase in photocurrent and responsivity at wavelengths above ≈380 nm, corresponding to a device response below the bandgap of 4h-SiC. We confirmed quantitatively an enhanced hybrid device behavior due to the application of QDs, laying the foundation for a novel approach at creating a QD sensitized solar cell.

Available for download on Monday, February 15, 2021