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Graduate Student Seminar - 04/27/2018

"Increasing Absorption in Metallic Optical Coatings with Epsilon-Near-Zero Materials"

by Lisa Krayer

Advisor:  Assoc. Professor Jeremy Munday

Friday, April 27, 2018 -- 12:00 p.m.
Large Conference Room, 1207 Energy Research Facility

Abstract:Expanding the bandwidth of silicon detectors is advantageous for many applications requiring optical energy conversion because silicon is a well understood, naturally abundant and relatively inexpensive material. Hot carriers generated from photons below silicon’s bandgap in metal contacts can reduce the effective bandgap to the Schottky barrier height because of current injection through the metal-semiconductor interface. However, for efficient photodetection the metal must be highly absorptive at long wavelengths and ultra-thin in order for the hot carriers to reach the Schottky interface with enough energy to traverse the barrier. Previous hot carrier photodetectors have required complicated nanostructuring to meet these requirements, increasing their fabrication cost which could prohibit their integration into commercial device design. We have demonstrated a cost effective, lithography free hot carrier photodetector that absorbs ~80% of broadband IR radiation in a planar, nanoscale back contact to silicon. We propose to further improve the absorption with the use of epsilon-near-zero materials to enhance the absorption resonance for near perfect absorption.

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