Identifying Radiative Polaritons in Thin Oxide Films with Experimental and Simulated Dispersion Relations Anita J. Vincent-Johnson 1, James S. Hammonds Jr. 2, Giovanna Scarel 1 1 Department of Physics and Astronomy, James Madison University, Harrisonburg, VA 2 Department of Mechanical Engineering, Howard University, Washington D.C.

Solar Radiation as an Alternate Energy Source VisibleInfrared Excitonspolaritons? Solar Spectrum

Polaritons in Thin Oxide Films IR beam Photon Phonon Thin Oxide Film (nm)

Types of Polaritons Radiative Polaritons k ω/k =c Surface Phonon Polaritons Radiative Polaritons

Surface Phonon Polaritons Crystal Interface (ω/k) 2 < c 2 k ω/k =c Surface Phonon Polaritons

Radiative Polaritons (RP) (ω/k) 2 > c 2 1.Theory * : Radiation 2.Reality: Heat Production k ω/k =c Radiative Polaritons * Kliewer et al., Phys. Rev. 150, 573 (1966)

Thermoelectric Device Seebeck Effect Radiative Polariton Radiation

Goal: Prove Radiative Polaritons Exist in Thin Oxide Films How?

Property of Radiative Polaritons ω = Re(ω)+i Im(ω) [Exp.] A=100%-R Fourier Transform Infrared Spectroscopy n θoθo IR Beam Reflection Detector

infrared radiation  oxide substrate air (layer 1) (layer 2) (layer 3) (layer 4) Al 2 O 3 (250nm) Al (23μm) Property of Radiative Polaritons ω = Re(ω)+i Im(ω) [Sim.]

Dispersion Relations Versus Polarization Versus Film Thickness

Experimental Spectra for 0TH Peak * Kliewer et al., Phys. Rev. 150, 573 (1966)

Simulated and Experimental Dispersion Relations for 0TH Peak * Kliewer et al., Phys. Rev. 150, 573 (1966)

Simulated Dispersion Relations for 0TH Peak for Various Film Thickness

Conclusion and Future Research Radiative Polaritons are present in our Thin Oxide Films Test and Exploit Heat Production of Radiative Polaritons Test different Oxides and Substrates

Acknowledgments Mr. Arthur G. Fovargue, James Madison University Prof. Brian H. Augustine, James Madison University Dr. Harry Hu, James Madison University Funding The NSF-REU Materials Program at JMU Grant DMR Research Corporation Science Department Development Grant 7957 DOD-ASSURE/NSF-REU grant # DMR James Madison University (JMU) Center for Materials Science Summer Research Grant 2011 from the JMU College of Sciences and Mathematics

Atomic Layer Deposition CH 3 terminated H terminated Ar-Purge (8 s) Ar-Purge (8 s) :TMA:CH 4 :H 2 O TMA (1s) H 2 O (1s) a-Al 2 O 3 layer on Al Substrate Thickness ~250nm Growth temperature 150 o C Al Substrate Al 2 O 3 Thin Film

Fourier Transform Infrared Spectroscopy 18 IR Beam n Transmission θoθo n θoθo IR Beam Reflection Detector A=100-T-R Absorption

19 Seebeck Effect Thermoelectric device (TEC) * transforms a temperature gradient into electricity 19 V + - T2T2 T1T1 material 2 T 2 > T 1 If hypothesis is correct the Seebeck effect will confirm this P=IV * Provided by Custom Thermoelectric, Bishopville, MD

infrared radiation  oxide substrate air (layer 1) (layer 2) (layer 3) (layer 4) E X E Al 2 O 3 (250nm) Al (23μm)