29 May 2015 Carbon Nanotube Based Detectors for THz Radiometry

Transcription

1 29 May 2015 Carbon Nanotube Based Detectors for THz Radiometry J.H. Lehman Na#onal Ins#tute of Standards and Technology 325 Broadway, Boulder, Colorado

2 Where and Who Boulder, CO Gaithersburg, MD Physical Measurement Laboratory Quantum Electronics and Photonics Division Nathan Tomlin, Malcolm White, Solomon Woods

3 Future Andreas Steiger, ChrisFan Monte, Jörg Hollandt Physikalisch- Technische Bundesanstalt, Berlin, Germany Free field, FTIR & far infrared/thz PTB - Berlin, Germany Photo: A. Steiger

4 Carbon Nanotubes Single-wall Carbon Nanotubes Not spectrally uniform Single sheet of graphene wrapped into a tube: microns in length, ~1-2 nm diameter, capped (Iijima, 1993). Multi-wall Carbon Nanotubes Concentric cylinders of graphite with a hollow center, capped (Iijima, 1991) Very spectrally uniform

5 Nanotube topologies mats composite arrays

6 Absorber Morphology, Black Coatings Nickel phosphorous Gold black nano fractal gold Bulk carbon nanotubes 1 µm 1 µm 1 µm Silicon Black silicon 1 µm A. Brenner and G. E. Riddell, J. Res. Natl. Bur. Stand. (U. S.), 1946, 37, R.J.C. Brown, P.J. Brewer and M.J.T. Milton, J. Mater. Chem., 2002, 12, Lehman, J.H., Theocharous, E., Eppeldauer, G., Pannell, C., Meas. Sci. Technol. 14, , (2003). J. E. Carey, C. H. Crouch, E. Mazur, Opt. & Phot. News, Feb (2003)

7 Absorber Properties 1. index ~ air (or vacuum) 2. Optically thick 3. Thermal diffusivity large α = k ρc k ~ 400 W/mK (big!) ρ ~ 7 kg/m 3 (small!) c ~ 400 J/kgK Lehman et al., Applied Optics, 50, , (2011)

8 EMA for Aligned Cylinders s > 10 nm ~ 10 µm p polarization, E perpendicular to tube (optical response depends on ε and ε for graphite) r ~ 5 nm s polarization, E directed along tube (optical response depends only on ε for graphite) * García-Vidal, et al., Phys. Rev. Lett., 78, (1997)

9 EMA, Calculated Results 100 spacing = 30 nm spacing = 17 nm low fill, large spacing Relative Responsivity (%) spacing = 14 nm high fill, small spacing Wavelength (nm) Based on index calculated from composite dielectric function; 60 µm thick, LiTaO 3, with nickel electrodes Theocharous, et al., 45, APPL. OPT (2006)

10 Vis/NIR reflectance * * * _ 2 µm _ 5 µm 0.1 % reflectance nm Tomlin et al., CARBON 74 (2014)

11 Low density, rough and low non-nt content water assisted CVD rough varying length varying angle Mizuno et al., PNAS, Chunnilall et al., Carbon, 50, , 2012.

12 FIR reflectance

13 Detectors

14 Pyroelectric Detectors 1 cm Theocharous, et al., Appl. Opt., 52, 2013

15 Thermopile forest 100 µm silicon pelfer

16 Thermopile

17 Radiometer Design heater heatsink thermometer T absorber weak thermal link 1. α 2. [V/W] optical absorption (1-loss) absolute response (from heater) T V 3. [V/W] tie points wavelength (µm)

18 Cryogenic Radiometer Design weak thermal link heater blackened cavity and absorber thermometer photo: courtesy Malcolm White Martin, et al.,, Metrologia, 21, 1985

19 Carbon nanotube electrical substitution bolometer radiometer heater absorber thermistor link Tomlin, et al., Metrologia 52 (2015)

20 Material DeposiFon CNT Fe Al 2 O 3 Mo SiO 2 Si Silicon Wafer (Ø75 mm) 1. Engineer and micromachine G (w, t, and l) 2. Grow SiO 2 3. Deposit Mo (all) 4. Wet etch to define Mo pattern (heater/electrodes) Pattern Photoresist 1. Deposit Al 2 O 3 2. Deposit Fe 3. Lift off Photoresist (acetone) 4. Grow CNTs

21 Material DeposiFon 75 mm

22 Planarnanotube electrical-substitution nanotube cryogenic radiometer radiometer Carbon electrical carbon substitution bolometer Figure 11. Schem showing VACNT pul not to scale. thermal conductan leads to a longer Figure 10. (a) VACNT at 4 K and (b) Mo at K temporal response due to52chopping the optical power ( 102 µw). The Tomlin, et al., Metrologia (2015) digitization in (a) is due to the low resolution of the oscilloscope. SPEED 9. Measuring o

23 Carbon nanotube electrical substitution bolometer radiometer electrical opfcal Tomlin, et al., Metrologia 52 (2015) EQUIVALENCE

24 Low-Temperature Nanotube Bolometer Behavior SuperconducFng TransiFon Near 4 K Tomlin, et al., Metrologia 52 (2015) SENSITIVITY

25 Carbon Nanotube Base Detectors Broad, efficient and uniform wavelength range visible to 500 micrometers (!?) (BRDF needed)

26 Carbon Nanotube Base Detectors Broad, efficient and uniform wavelength range visible to 500 micrometers (!?) (BRDF needed) τ ~ 1 ms Fast (suitable for FTIR)

27 Carbon Nanotube Base Detectors Broad, efficient and uniform wavelength range visible to 500 micrometers (!?) (BRDF needed) τ ~ 1 ms Fast (suitable for FTIR) Scalable, reproducible Optimize per application fiber, space, few photon (open mind required)

28 PTB Berlin (THz/FIR) NIST-Boulder (optical fiber) GREYC / Univ. Caen (speed) NIST-Gaithersburg (MIR/speed) NIST Nanotube Bolometer Workshop, July 22, 23, 24, 2015 Boulder, Colorado, USA hmp:// bolometer- workshop.cfm