J. G. Eden. University of Illinois. University of Illinois. Laboratory for Optical Physics and Engineering

Transcription

1 NEW OPPORTUNITIES IN PHOTONICS APPLICATIONS : MICROPLASMA DEVICES AND ARRAYS FABRICATED IN SEMICONDUCTORS, CERAMIC AND POLYMER/METAL MULTILAYER STRUCTURES J. G. Eden

2 MICROPLASMAS: AT THE INTERSECTION OF OPTOELECTRONICS, MICROFABRICATION, AND PLASMA SCIENCE PLASMA SCIENCE New realm of discharge operation and characteristics MICROPLASMAS PHOTONICS MATERIALS SCIENCE, MICRO- AND NANOFABRICATION Broad array of applications

3 SUMMARY Glow discharges confined to mesoscopic dimensions ( < 10 ~ 100 µm) Microcavity volumes: nanoliters picoliters A variety of atomic and molecular emitters are available (VUV ~ IR) Can be operated continuously at gas pressures beyond one atmosphere at power loadings exceeding 100 kw/cm3 Leveraging MEMs and semiconductor processes for fabrication of devices and arrays Emphasis on processes amenable to mass production

4 GENERAL CONSIDERATIONS Macroscopic Annular Cathode Thin Film Structure d Disk Anode Discharge microcavity dimensions ( d ) on µm scale As d, surface area / volume : Importance of microcavity design

5 Semiconductor Devices

6 REPRESENTATIVE Si DEVICE STRUCTURES anode dielectric cathode Planar Si Electrode Inverted Pyramidal Electrode DRIE Electrode

7 SEMICONDUCTOR ARRAYS Inverted Square Pyramidal Cathode 400 Torr Ne 1200 Torr Ne

8 EMISSION UNIFORMITY: DC EXCITATION, ATOMIC AND MOLECULAR EMITTERS Ne Ar Ar/N2

9 LARGE ARRAYS FOR AC EXCITATION

10 ARRAY : 4 cm2 OF ACTIVE AREA

11 ARRAY INTENSITY CONTOUR Arrays Uniformity : Better than 10 %

12 VOLTAGE-CURRENT CHARACTERISTICS : ARRAY x kh z T o rr V o lta g e ( V p - p ) C u rre n t (m A, R M S ) 30

13 1 5 khz 10 2 RMS RM S T o t a l P o w e r C o n s u m p t io n ( W ) T o rr N e -2 N o r m a liz e d P o w e r C o n s u m p t io n ( W - c m ) POWER CONSUMPTION 3 N u m b e r o f P ix e ls

14 A QUARTER MILLION PIXEL ARRAY : 25 cm2 OF ACTIVE AREA

15 ARRAY OPERATING in Ne 700 Torr Ne

16 ARRAY OPERATING in Ne 700 Torr Ne

17 PIXEL UNIFORMITY Attenuation with ND Filter

18 DRIE Si Devices (10 µm)2 Single (30 µm)2 10 X 11 arrays (30 µm)2 Single 900 Torr Ne

19 I-V Characteristics (10 µm)2 Si DRIE Device T orr N e V o l t a g e (V ) µm Ni 305 Polyimide µm SiO2 Si C u rre n t ( µ A )

20 Xe/O2 Microdischarges in 30 µm DRIE devices O2 10 mtorr

21 N Depletion Region Plasma Excitation of a Microdischarge with a Reverse-Biased PN Junction W P d = 300 µm, 180 V, 0.45 ma 200 Torr Neon

22 25 25 Pixel Array in Glass

23 Fresnel Arrays 400 Torr Ne Device Separation < Coherence Length

24 MICRODISCHARGE PHOTODETECTORS With Illumination 246.7V, ma ( V, ma m)2 device, 500 Torr Neon

25 Photosensitivity Photosensitivity (A/W) 2 (100 µm) Device 500 Torr Ne λ = 780 nm Active Plasma Device Entire Device Die Input Power (µw)

26 Spectral Response 4.0 DCD = 36 ma/cm Photosensitivity (A/W) DCD = 27 ma/cm DCD = 62 ma/cm 3.0 DCD = 58 ma/cm (50 µm) Device, 800 Torr Ne (100 µm) Device, 500 Torr Ne Wavelength (nm)

27 Spectral Response Photosensitivity (A/W) 4.0 Scaled APD Response (100 µm)2, Active Plasma Device 2 (50 µm), Active Plasma Device Wavelength (nm)

28 Band Diagram

29 Ceramic Devices

30 MULTISTAGE, MONOLITHIC CERAMIC MICRODISCHARGE DEVICE d anode pad anode cathode anode cathode ceramic layer cathode pad Pre-fired Fired

31 PLANAR ARRAY ELECTRODE GEOMETRY Electrode spacing is ~100 µm Parallel plate annular electrode design yields more electrode area Better device stability Longer lifetime Reduced field enhancement Individually-ballasted pixels Fabrication by screen printing

32 300 Torr Xe

33 LINEAR ARRAY CW or Pulsed Excitation Bore: 80 X 360 µm2 Active Length ~1 cm

34 600 Torr Ne

35 Intensity Gain at nm: Xe V 500 V 800 V Wavelength (nm)

36 Nanoporous Dielectrics for Microcavity Devices Pore diameter: tens~hundreds of nm

37 Multilayer Al/Al2O3 Microplasma Array 100 µm V Al2O3 Al 200 µm

38 3 3 Array Operating in Ne and Ar/N2 700 Torr Ne 500 Torr Ar/N2 (3%)

39 Flexible Device and Arrays

40 Thin Film Self-Ballasted Microdischarge Arrays d = 100 µm Dielectric Anode V 30 ~ 40 µm Cathode Layer (Ni) Dielectric Conducting Substrate Resistive Layer

41 d = 100 µm, 500 Torr Ne 20 mm 148.2V DC, 15 ma

42 13 ~ 30 µm DEVICES Metal/Polymer Structure 30 µm dia. Microdischarge Device 30 µm 30 µm ND filter

43 Devices Approaching Cellular Dimensions 900 Torr Neon

44 Flexible Large Arrays ~ 100 µm dia. 500 Torr Ne

45 SEALED LARGE ARRAY: ARRAY in 3 cm2 OF ACTIVE AREA 100 µm dia. Pixels 760 Torr Ne 10 khz AC, 800 Vp-p

46 ADDRESSABLE FLEXIBLE ARRAY

47 AIR DISCHARGE DEVICES Ni / BN / Ni d = 100 µm, DC 450 V, 4 ma

48 MICRODISCHARGE ARRAY ASSISTED IGNITION OF A HIGH PRESSURE DISCHARGE

49 3.0 Ar d=400 µm 2.5 Vs (kv) 2.0 L=3.5 cm 1.5 Microdischarge Array 1.0 OFF I = 1 ma 1.5 ma 2 ma 3 ma L=1.0 cm Pressure (Torr)

50 Microdischarge Device with Carbon Nanotubes Ni screen anode BN (~70 µm) Ni cathode (50 µm) 200 µm CNT Type I CNT 25 µm 200 µm Type II Si 2nd cathode SEM Image of Microcavity in Type I

51 Microdischarge Device with CNTs Type I Before Operation 400 Torr Ne

52 140 I-V Characteristics T o rr N e Type I N i / B N ( 7 0 µm ) / N i C u rre n t (m A ) T o rr N e T o rr N e C u rre n t (m A ) Type II Without CNTs D e v ic e V o lt a g e ( V ) D e v ic e V o lt a g e ( V ) 150 D e v ic e V o lt a g e ( V ) C u rre n t (m A )

53 Efficiency vs. Ignition Voltage 9.6 W it h o u t C N T s S ta rtin g V o lta g e (V ) R e la tiv e R a d ia tiv e E ffic ie n c y T yp e I W ith o u t C N T s T yp e I T y p e II P Ne (T o rr) Efficiency improved up to ~9 % Ignition voltage reduced by ~18% 400 P Ne 500 (T o rr)

54 APPLICATIONS Microdischarges

55 WHERE DO WE GO FROM HERE? d < 10 µm < 1 µm Full Implementation of Nanotechnology d λ : QED Effects Optical Integration of Emitters With Waveguides, Micro-Reactors Operation at Extremely High Pressures ( > 5 atm) : Clusters, New Regime of Molecular Excitation

56 RESEARCH TEAM UNIVERSITY OF ILLINOIS S. J. Park N. P. Ostrom K.-F. Chen C. J. Wagner K. S. Kim K. Kunze M. Leach ANVIK CORPORATION M. Zemel M. Klosner K. Jain EWING TECHNOLOGY ASSOCIATES J. J. Ewing P. von Allmen (now at NASA, JPL) D. L. Wilcox F. Zenhausern M. Oliver D. Sadler C. Jensen MOTOROLA LABORATORIES (TEMPE, AZ) CAVITON C. Herring D. Kellner CAMBRIDGE, UK K.-H. Park

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