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Tunable intraband optical conductivity and polarization-dependent epsilon-near-zero behavior in black phosphorus

Biswas, Souvik and Whitney, William S. and Grajower, Meir Y. and Watanabe, Kenji and Taniguchi, Takashi and Bechtel, Hans A. and Rossman, George R. and Atwater, Harry A. (2020) Tunable intraband optical conductivity and polarization-dependent epsilon-near-zero behavior in black phosphorus. . (Unpublished)

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Black phosphorus (BP) offers considerable promise for infrared and visible photonics. Efficient tuning of the bandgap and higher subbands in BP by modulation of the Fermi level or application of vertical electric fields has been previously demonstrated, allowing electrical control of its above bandgap optical properties. Here, we report modulation of the optical conductivity below the band-gap (5-15 um) by tuning the charge density in a two-dimensional electron gas (2DEG) induced in BP, thereby modifying its free carrier dominated intraband response. With a moderate doping density of 7x10¹²/cm⁻² we were able to observe a polarization dependent epsilon-near-zero behavior in the dielectric permittivity of BP. The intraband polarization sensitivity is intimately linked to the difference in effective fermionic masses along the two crystallographic directions, as confirmed by our measurements. Our results suggest the potential of multilayer BP to allow new optical functions for emerging photonics applications.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Whitney, William S.0000-0001-5269-2967
Watanabe, Kenji0000-0003-3701-8119
Rossman, George R.0000-0002-4571-6884
Atwater, Harry A.0000-0001-9435-0201
Additional Information:The authors would like to thank Dr. Qiushi Guo regarding preliminary discussions about this project, Joeson Wong for discussions regarding transfer matrices, Ghazaleh Kafaie Shirmanesh for help with printed circuit boards for electrical measurements and Dr. Laura Kim for providing LabVIEW script to perform electrical measurements. The authors gratefully acknowledge support from the Department of Energy-Office of Science under grant DE-FG02-07ER46405. This research used resources of the Advanced Light Source, a U.S. DOE Office of Science User Facility under contract no. DE-AC02-05CH11231. K.W. and T.T. acknowledge support from the Elemental Strategy Initiative conducted by the MEXT, Japan, Grant Number JPMXP0112101001, JSPS KAKENHI Grant Numbers JP20H00354 and the CREST (JPMJCR15F3), JST. Author contributions: S.B., W.S.W. and H.A.A conceived the project. S.B. and W.S.W. worked on fabrication, measurements and analysis of preliminary data. S.B. fabricated, measured and analyzed data from final samples. M.Y.G. assisted in electrical and optical measurements. S.B., W.S.W. and M.Y.G. discussed the implications of the results. H.A.A. supervised the project. H.A.B. assisted with additional and complementary measurements done at the ALS, Berkeley. K.W. and T.T. provided hBN and BP crystals. G.R.R supervised some of the optical measurements. S.B. wrote the manuscript and all authors provided important feedback. The authors declare that they have no competing interests. Data and materials availability: All data required to evaluate the conclusions in the manuscript are available in the main text and/or Supplementary Materials. Additional data may be requested from the authors.
Funding AgencyGrant Number
Department of Energy (DOE)DE-FG02-07ER46405
Department of Energy (DOE)DE-AC02-05CH11231
Ministry of Education, Culture, Sports, Science and Technology (MEXT)JPMXP0112101001
Japan Society for the Promotion of Science (JSPS)JP20H00354
Japan Science and Technology AgencyJPMJCR15F3
Record Number:CaltechAUTHORS:20201005-140039939
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105809
Deposited By: Tony Diaz
Deposited On:05 Oct 2020 21:24
Last Modified:05 Oct 2020 21:24

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