Deep ultra-violet plasmonics: exploiting momentum-resolved electron energy loss spectroscopy to probe germanium
Abstract
Germanium is typically used for solid-state electronics, fiber-optics, and infrared applications, due to its semiconducting behavior at optical and infrared wavelengths. In contrast, here we show that the germanium displays metallic nature and supports propagating surface plasmons in the deep ultraviolet (DUV) wavelengths, that is typically not possible to achieve with conventional plasmonic metals such as gold, silver, and aluminum. We measure the photonic band spectrum and distinguish the plasmonic excitation modes: bulk plasmons, surface plasmons, and Cherenkov radiation using a momentum-resolved electron energy loss spectroscopy. The observed spectrum is validated through the macroscopic electrodynamic electron energy loss theory and first-principles density functional theory calculations. In the DUV regime, intraband transitions of valence electrons dominate over the interband transitions, resulting in the observed highly dispersive surface plasmons. We further employ these surface plasmons in germanium to design a DUV radiation source based on the Smith-Purcell effect. Our work opens a new frontier of DUV plasmonics to enable the development of DUV devices such as metasurfaces, detectors, and light sources based on plasmonic germanium thin films.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Mar 31, 2022
- Source ID
- 10.1364/oe.447017
Entities
People
- Farhad Khosravi
- Kai Cui
- Limei Qi
- Marek Malac
- Neda Nazemifard
- Rajib Rahman
- Ravichandra Jagannath
- Sathwik Bharadwaj
- Suraj Iyer
- Wenbo Sun
- Zohreh Poursoti
- Zubin Jacob
Organizations
- Defense Advanced Research Projects Agency
- KLA Corporation
- National Research Council Canada
- National Science Foundation
- Purdue University
- University of Alberta
- University of New South Wales