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ZnO /metal layered 3D Photonic crystals

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ZnO /metal layered 3D Photonic crystals. Michael McMaster , Dr. Tom Oder, Dr. Donald Priour. Dept. of Physics and Astronomy, Youngstown State University, Youngstown, OH. What to Expect. What is a Photonic Crystal? Experimental Procedure Modeling/Results Conclusion. Photonic Crystal.

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slide1

ZnO/metal layered 3D Photonic crystals

Michael McMaster, Dr. Tom Oder, Dr. Donald Priour

Dept. of Physics and Astronomy,

Youngstown State University, Youngstown, OH

slide2

What to Expect

  • What is a Photonic Crystal?
  • Experimental Procedure
  • Modeling/Results
  • Conclusion
slide3

Photonic Crystal

  • “Photonic crystals are materials patterned with a periodicity in dielectric constant, which can create a range of ‘forbidden’ frequencies called a photonic bandgap. Photons with energies lying in the bandgap cannot propagate through the medium. This provides the opportunity to shape and mould the flow of light for photonic information technology.”
    • J.D. Joannopoulos, Pierre R. Villeneuve & Shanhui Fan
  • Applications include
  • Waveguides
  • LED light extraction
  • Ultrafast photonic crystal nanocavity laser
  • High speed communication
  • High speed information processing
slide4

CallophrysGryneus

Vinodkumar et. Al. (2010)

slide5

Peacock

Paridessesostris

Weevil and two Longhorns

Vinodkumar et. Al. (2010)

CERN Courier (2005)

Vigneron et. Al. (2012)

slide8

ZnO/Cr and ZnO/Al Multilayer Films

  • Substrate: double-side polished sapphire
  • Base Pressure: 10-7 mtorr
  • Preheat temperature:~700°C
  • Depositions temperature: 300°C
  • Deposition pressure: 10 mtorr
  • Ambient gas: Ar
  • Flow Rate: 10 sccm
  • Presputter: 3 min
  • ZnO Buffer Layer: 250 nm
  • Layer thicknesses:
    • ZnO/Cr (120 nm/12 nm)x10
    • ZnO/Cr (90 nm/ 5nm) x10
    • ZnO/Al (170 nm/ 5nm) x8
slide9

How can we make 3-D Photonic Crystals?

Bottom Up

Top Down

FIB

Holes in 1-D crystals

Accurate, small feature size

  • Shadow mask sputtering
  • Periodic Array of Pillars
  • Quick and easy
slide10

Some Quick Physics Facts

  • Index of Refraction:
  • Snell’s law
  • The Electric Field Equation:
slide11

Mathematical Interlude

n1 n2 n3 … nN-1nN ns

A0 A1 A2 … … AN As

B0 B1 B2 … … BNBs

x0 x1 x2 … … xNxs

The Electric Field can be shown for different refractive indices as:

So we get a vector representing the amplitudes of the wave function.

Yeh. (2004)

slide12

Mathematical Interlude (continued)

We can describe light at the interface of materials with different refractive indices with the dynamical matrices:

so that light passing through the interface responds such that

.

Also, as it travels through a material, the change is shown by the transfer matrix:

Yeh. (2004)

slide13

Mathematical Interlude (Recap)

  • By acting on the vector representing light passing through the system with the matrices describing the environment we can predict the transmission spectrum.
  • Recall:

But metals have an imaginary index of refraction (n) so

let’s write:

But Φhas real an imaginary parts Re(Φ) and Im(Φ) so

where we see the Decay term.

Yeh. (2004)

slide14

1-D Photonic Crystals

  • Refractive Indices in Visible Spectrum
    • ZnO 2.0
    • Cr 3.2
    • Al 1.3
  • Layer thicknesses of samples:
    • ZnO/Cr (120 nm/12 nm)x10
    • ZnO/Cr (90 nm/ 5nm) x10
    • ZnO/Al (170 nm/ 5nm) x8
slide15

Transmission Spectrum

Actual Transmission Spectrum

Theoretical Transmission Spectrum

?

slide16

After Annealing

ZnO/Cr 1-D photonic Crystal

Theoretical Model

slide17

After Annealing

ZnO/Cr 1-D photonic Crystal

Theoretical Model

slide18

Remember those cosines?

ZnO/Cr (120nm/12nm)x10

Theoretical Model

Photonic Crystal

Not a Photonic Crystal

slide19

We can Control the Band-Gap!

(this Time in Blue)

Band-Gap

ZnO/Cr 1-D photonic Crystal

Theoretical Model

slide20

Aluminum

  • Band-gap is maximized when n1d1=n2d2
  • nZnO=2.0 nAl=1.3
    • ZnO/Al (170 nm/ 5nm) x8
  • We predict a smaller band-gap

ZnO/Al 1-D photonic Crystal

Theoretical

Joannopoulos et. Al. (2008)

slide21

EDX Results (Not Chromium Oxide)

ZnO/Cr (120 nm/12 nm)x10

Expected Transmission Spectrum if Chromium had oxidized.

(CrO3 refractive index 2.55)

ZnO/Cr (90 nm/ 5nm) x10

ZnO/Al (170 nm/ 5nm) x8

slide23

4-Point Probe Results

Bulk Resistivity (Ω∙cm)

Pre Annealing Post Annealing

ZnO/Cr (120 nm/12 nm)x10 .012 15

ZnO/Cr (90 nm/ 5nm) x10 .0027 310

ZnO/Al (170 nm/ 5nm) x8 too resistive .095

slide24

What Next???

  • Produce 3-D photonic crystals
  • using Shadow mask or FIB
  • Model in higher dimension
  • TEM/AFM for layer thickness

What we Expect

What we Hope For

  • Evidence of 3-D from diffraction pattern
  • Measureable band-gaps in oblique directions
  • Improved modeling
  • both polar and radial angle band-gap dependance
  • Predict band-gap
  • Test the effect of electric field on optical the band-gap
slide25

References

  • VinodkumarSaranathan, Chinedum O. Osuji, Simon G. J. Mochrie, HeesoNoh, Suresh Narayanan, Alec Sandy, Eric R. Dufresne, and Richard O. Prum. Structure, function, and self-assembly of single network gyroid (I4132) photonic crystals in butterfly wing scales PNAS 107 (26) 11676-11681 (2010).
  • Joannopoulos, John D., Steven G. Johnson, Joshua N. Winn, Robert D. Meade. Photonic Crystals Modeling the Flow of Light Second Edition. Princeton University Press (2008).
  • Yeh,Pochi. Optical Waves In Layered Media: 2nd (second) Edition. Whiley Press (2004).
  • Peacock feathers prove photonic crystals cast brown light in nature. CERN Courier. Aug 22, 2005
    • JoannopoulosJ.D. , Pierre R. Villeneuve and ShanhuiFan. Photonic Crystals: putting a new twist on light. Nature 386 (13) 143-149 (1997)
    • Vigneron, Jean Pol, and Priscilla Simonis. Natural photonic crystals.Physica B Condensed Matter 407 (20) 4032-4036 (2012)
slide26

Acknowledgements

  • We gratefully acknowledge support of funds from NSF (DMR#1006083) and from the State of Ohio (Third Frontier - RC-SAM).
  • Support and funds from Youngstown State University
  • I would also like to thank Dr. Jim Andrews, Jessica Shipman and Matt Kelly and Dr. George Yates for helping with this project.
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