Abstract

Experimental long wavelength infrared spectral response characterization of a narrowband Salisbury screen absorber suitable for use in microbolometer focal plane arrays is presented. We have demonstrated a microfabricated germanium dielectric support structure layer that replaces the usual silicon nitride structural layer in microbolometers. The fabricated Salisbury screen absorber consists of a chromium resistive sheet as an absorber layer above a germanium dielectric/air-gap/interference structure. In order to produce wavelength-selective narrowband absorption, the general design rules for the germanium dielectric supported Salisbury screen show that the thickness of the air gap should be a half wavelength thick and the optical thickness of the germanium layer a quarter dielectric wavelength thick.

© 2014 Optical Society of America

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  1. S. D. Gunapala, S. V. Bandara, J. K. Liu, J. M. Mumolo, C. J. Hill, S. B. Rafol, D. Salazar, J. Woollaway, P. D. LeVan, and M. Z. Tidrow, “Towards dualband megapixel QWIP focal plane arrays,” Infrared Phys. Technol. 50, 217–226 (2007).
    [CrossRef]
  2. Z. Ye, J. C. Campbell, Z. Chen, E.-T. Kim, and A. Madhukar, “A normal-incidence InAs self-assembled quantum-dot infrared photodetectors with a high detectivity,” IEEE J. Quantum Electron. 38, 1234–1237 (2002).
    [CrossRef]
  3. H. Hara, N. Kishi, and H. Iwaoka, “Silicon bolometer and micro variable infrared filter for CO2 measurement,” in Proceedings of IEEE Conference on Optical MEMS (IEEE, 2000), pp. 139–140.
  4. S. W. Han, J. W. Kim, Y. S. Sohn, and D. P. Neikirk, “Design of infrared wavelength-selective microbolometers using planar multimode detectors,” Electron. Lett. 40, 1410–1411 (2004).
    [CrossRef]
  5. J.-Y. Jung, J. Y. Park, and D. P. Neikirk, “Wavelength-selective infrared detectors based on cross patterned resistive sheets,” Proc. SPIE 7298, 72980L (2009).
    [CrossRef]
  6. T. Maier and H. Bruckl, “Wavelength-tunable microbolometers with metamaterial absorbers,” Opt. Lett. 34, 3012–3014 (2009).
    [CrossRef]
  7. X. Liu, T. Starr, A. F. Starr, and W. J. Padilla, “Infrared spatial; and frequency selective metamaterial with near-unity absorbance,” Phys. Rev. Lett. 104, 207403 (2010).
    [CrossRef]
  8. J. A. Mason, S. Smith, and D. Wasserman, “Strong absorption and selective thermal emission from a midinfrared metamaterial,” Appl. Phys. Lett. 98, 241105 (2011).
    [CrossRef]
  9. Y. Wang, B. J. Potter, and J. J. Talghader, “Coupled absorption filters for thermal detectors,” Opt. Lett. 31, 1945–1947 (2006).
    [CrossRef]
  10. R. A. Wood, “Uncooled thermal imaging with monolithic silicon focal planes,” Proc. SPIE 2020, 322–329 (1993).
    [CrossRef]
  11. B. E. Cole, “Microstructure design for high IR sensitivity,” U. S. patent5,286,976 (15February1994).
  12. M. K. Gunde and M. Macek, “Infrared optical constants and dielectric response functions of silicon nitride and oxynitride films,” Phys. Status Solidi A 183, 439–449 (2001).
    [CrossRef]
  13. E. D. Palik, Handbook of Optical Constants of Solids (Academic, 1985).
  14. D. M. Pozar, Microwave Engineering (Addison-Wesley, 1993).
  15. A. Bagolini, L. Pakula, T. L. M. Pham, P. J. French, and P. M. Sarro, “Polyimide sacrificial layer and novel materials for post-processing surface micromachining,” J. Micromech. Microeng. 12, 385–389 (2002).
    [CrossRef]

2011 (1)

J. A. Mason, S. Smith, and D. Wasserman, “Strong absorption and selective thermal emission from a midinfrared metamaterial,” Appl. Phys. Lett. 98, 241105 (2011).
[CrossRef]

2010 (1)

X. Liu, T. Starr, A. F. Starr, and W. J. Padilla, “Infrared spatial; and frequency selective metamaterial with near-unity absorbance,” Phys. Rev. Lett. 104, 207403 (2010).
[CrossRef]

2009 (2)

J.-Y. Jung, J. Y. Park, and D. P. Neikirk, “Wavelength-selective infrared detectors based on cross patterned resistive sheets,” Proc. SPIE 7298, 72980L (2009).
[CrossRef]

T. Maier and H. Bruckl, “Wavelength-tunable microbolometers with metamaterial absorbers,” Opt. Lett. 34, 3012–3014 (2009).
[CrossRef]

2007 (1)

S. D. Gunapala, S. V. Bandara, J. K. Liu, J. M. Mumolo, C. J. Hill, S. B. Rafol, D. Salazar, J. Woollaway, P. D. LeVan, and M. Z. Tidrow, “Towards dualband megapixel QWIP focal plane arrays,” Infrared Phys. Technol. 50, 217–226 (2007).
[CrossRef]

2006 (1)

2004 (1)

S. W. Han, J. W. Kim, Y. S. Sohn, and D. P. Neikirk, “Design of infrared wavelength-selective microbolometers using planar multimode detectors,” Electron. Lett. 40, 1410–1411 (2004).
[CrossRef]

2002 (2)

Z. Ye, J. C. Campbell, Z. Chen, E.-T. Kim, and A. Madhukar, “A normal-incidence InAs self-assembled quantum-dot infrared photodetectors with a high detectivity,” IEEE J. Quantum Electron. 38, 1234–1237 (2002).
[CrossRef]

A. Bagolini, L. Pakula, T. L. M. Pham, P. J. French, and P. M. Sarro, “Polyimide sacrificial layer and novel materials for post-processing surface micromachining,” J. Micromech. Microeng. 12, 385–389 (2002).
[CrossRef]

2001 (1)

M. K. Gunde and M. Macek, “Infrared optical constants and dielectric response functions of silicon nitride and oxynitride films,” Phys. Status Solidi A 183, 439–449 (2001).
[CrossRef]

1993 (1)

R. A. Wood, “Uncooled thermal imaging with monolithic silicon focal planes,” Proc. SPIE 2020, 322–329 (1993).
[CrossRef]

Bagolini, A.

A. Bagolini, L. Pakula, T. L. M. Pham, P. J. French, and P. M. Sarro, “Polyimide sacrificial layer and novel materials for post-processing surface micromachining,” J. Micromech. Microeng. 12, 385–389 (2002).
[CrossRef]

Bandara, S. V.

S. D. Gunapala, S. V. Bandara, J. K. Liu, J. M. Mumolo, C. J. Hill, S. B. Rafol, D. Salazar, J. Woollaway, P. D. LeVan, and M. Z. Tidrow, “Towards dualband megapixel QWIP focal plane arrays,” Infrared Phys. Technol. 50, 217–226 (2007).
[CrossRef]

Bruckl, H.

Campbell, J. C.

Z. Ye, J. C. Campbell, Z. Chen, E.-T. Kim, and A. Madhukar, “A normal-incidence InAs self-assembled quantum-dot infrared photodetectors with a high detectivity,” IEEE J. Quantum Electron. 38, 1234–1237 (2002).
[CrossRef]

Chen, Z.

Z. Ye, J. C. Campbell, Z. Chen, E.-T. Kim, and A. Madhukar, “A normal-incidence InAs self-assembled quantum-dot infrared photodetectors with a high detectivity,” IEEE J. Quantum Electron. 38, 1234–1237 (2002).
[CrossRef]

Cole, B. E.

B. E. Cole, “Microstructure design for high IR sensitivity,” U. S. patent5,286,976 (15February1994).

French, P. J.

A. Bagolini, L. Pakula, T. L. M. Pham, P. J. French, and P. M. Sarro, “Polyimide sacrificial layer and novel materials for post-processing surface micromachining,” J. Micromech. Microeng. 12, 385–389 (2002).
[CrossRef]

Gunapala, S. D.

S. D. Gunapala, S. V. Bandara, J. K. Liu, J. M. Mumolo, C. J. Hill, S. B. Rafol, D. Salazar, J. Woollaway, P. D. LeVan, and M. Z. Tidrow, “Towards dualband megapixel QWIP focal plane arrays,” Infrared Phys. Technol. 50, 217–226 (2007).
[CrossRef]

Gunde, M. K.

M. K. Gunde and M. Macek, “Infrared optical constants and dielectric response functions of silicon nitride and oxynitride films,” Phys. Status Solidi A 183, 439–449 (2001).
[CrossRef]

Han, S. W.

S. W. Han, J. W. Kim, Y. S. Sohn, and D. P. Neikirk, “Design of infrared wavelength-selective microbolometers using planar multimode detectors,” Electron. Lett. 40, 1410–1411 (2004).
[CrossRef]

Hara, H.

H. Hara, N. Kishi, and H. Iwaoka, “Silicon bolometer and micro variable infrared filter for CO2 measurement,” in Proceedings of IEEE Conference on Optical MEMS (IEEE, 2000), pp. 139–140.

Hill, C. J.

S. D. Gunapala, S. V. Bandara, J. K. Liu, J. M. Mumolo, C. J. Hill, S. B. Rafol, D. Salazar, J. Woollaway, P. D. LeVan, and M. Z. Tidrow, “Towards dualband megapixel QWIP focal plane arrays,” Infrared Phys. Technol. 50, 217–226 (2007).
[CrossRef]

Iwaoka, H.

H. Hara, N. Kishi, and H. Iwaoka, “Silicon bolometer and micro variable infrared filter for CO2 measurement,” in Proceedings of IEEE Conference on Optical MEMS (IEEE, 2000), pp. 139–140.

Jung, J.-Y.

J.-Y. Jung, J. Y. Park, and D. P. Neikirk, “Wavelength-selective infrared detectors based on cross patterned resistive sheets,” Proc. SPIE 7298, 72980L (2009).
[CrossRef]

Kim, E.-T.

Z. Ye, J. C. Campbell, Z. Chen, E.-T. Kim, and A. Madhukar, “A normal-incidence InAs self-assembled quantum-dot infrared photodetectors with a high detectivity,” IEEE J. Quantum Electron. 38, 1234–1237 (2002).
[CrossRef]

Kim, J. W.

S. W. Han, J. W. Kim, Y. S. Sohn, and D. P. Neikirk, “Design of infrared wavelength-selective microbolometers using planar multimode detectors,” Electron. Lett. 40, 1410–1411 (2004).
[CrossRef]

Kishi, N.

H. Hara, N. Kishi, and H. Iwaoka, “Silicon bolometer and micro variable infrared filter for CO2 measurement,” in Proceedings of IEEE Conference on Optical MEMS (IEEE, 2000), pp. 139–140.

LeVan, P. D.

S. D. Gunapala, S. V. Bandara, J. K. Liu, J. M. Mumolo, C. J. Hill, S. B. Rafol, D. Salazar, J. Woollaway, P. D. LeVan, and M. Z. Tidrow, “Towards dualband megapixel QWIP focal plane arrays,” Infrared Phys. Technol. 50, 217–226 (2007).
[CrossRef]

Liu, J. K.

S. D. Gunapala, S. V. Bandara, J. K. Liu, J. M. Mumolo, C. J. Hill, S. B. Rafol, D. Salazar, J. Woollaway, P. D. LeVan, and M. Z. Tidrow, “Towards dualband megapixel QWIP focal plane arrays,” Infrared Phys. Technol. 50, 217–226 (2007).
[CrossRef]

Liu, X.

X. Liu, T. Starr, A. F. Starr, and W. J. Padilla, “Infrared spatial; and frequency selective metamaterial with near-unity absorbance,” Phys. Rev. Lett. 104, 207403 (2010).
[CrossRef]

Macek, M.

M. K. Gunde and M. Macek, “Infrared optical constants and dielectric response functions of silicon nitride and oxynitride films,” Phys. Status Solidi A 183, 439–449 (2001).
[CrossRef]

Madhukar, A.

Z. Ye, J. C. Campbell, Z. Chen, E.-T. Kim, and A. Madhukar, “A normal-incidence InAs self-assembled quantum-dot infrared photodetectors with a high detectivity,” IEEE J. Quantum Electron. 38, 1234–1237 (2002).
[CrossRef]

Maier, T.

Mason, J. A.

J. A. Mason, S. Smith, and D. Wasserman, “Strong absorption and selective thermal emission from a midinfrared metamaterial,” Appl. Phys. Lett. 98, 241105 (2011).
[CrossRef]

Mumolo, J. M.

S. D. Gunapala, S. V. Bandara, J. K. Liu, J. M. Mumolo, C. J. Hill, S. B. Rafol, D. Salazar, J. Woollaway, P. D. LeVan, and M. Z. Tidrow, “Towards dualband megapixel QWIP focal plane arrays,” Infrared Phys. Technol. 50, 217–226 (2007).
[CrossRef]

Neikirk, D. P.

J.-Y. Jung, J. Y. Park, and D. P. Neikirk, “Wavelength-selective infrared detectors based on cross patterned resistive sheets,” Proc. SPIE 7298, 72980L (2009).
[CrossRef]

S. W. Han, J. W. Kim, Y. S. Sohn, and D. P. Neikirk, “Design of infrared wavelength-selective microbolometers using planar multimode detectors,” Electron. Lett. 40, 1410–1411 (2004).
[CrossRef]

Padilla, W. J.

X. Liu, T. Starr, A. F. Starr, and W. J. Padilla, “Infrared spatial; and frequency selective metamaterial with near-unity absorbance,” Phys. Rev. Lett. 104, 207403 (2010).
[CrossRef]

Pakula, L.

A. Bagolini, L. Pakula, T. L. M. Pham, P. J. French, and P. M. Sarro, “Polyimide sacrificial layer and novel materials for post-processing surface micromachining,” J. Micromech. Microeng. 12, 385–389 (2002).
[CrossRef]

Palik, E. D.

E. D. Palik, Handbook of Optical Constants of Solids (Academic, 1985).

Park, J. Y.

J.-Y. Jung, J. Y. Park, and D. P. Neikirk, “Wavelength-selective infrared detectors based on cross patterned resistive sheets,” Proc. SPIE 7298, 72980L (2009).
[CrossRef]

Pham, T. L. M.

A. Bagolini, L. Pakula, T. L. M. Pham, P. J. French, and P. M. Sarro, “Polyimide sacrificial layer and novel materials for post-processing surface micromachining,” J. Micromech. Microeng. 12, 385–389 (2002).
[CrossRef]

Potter, B. J.

Pozar, D. M.

D. M. Pozar, Microwave Engineering (Addison-Wesley, 1993).

Rafol, S. B.

S. D. Gunapala, S. V. Bandara, J. K. Liu, J. M. Mumolo, C. J. Hill, S. B. Rafol, D. Salazar, J. Woollaway, P. D. LeVan, and M. Z. Tidrow, “Towards dualband megapixel QWIP focal plane arrays,” Infrared Phys. Technol. 50, 217–226 (2007).
[CrossRef]

Salazar, D.

S. D. Gunapala, S. V. Bandara, J. K. Liu, J. M. Mumolo, C. J. Hill, S. B. Rafol, D. Salazar, J. Woollaway, P. D. LeVan, and M. Z. Tidrow, “Towards dualband megapixel QWIP focal plane arrays,” Infrared Phys. Technol. 50, 217–226 (2007).
[CrossRef]

Sarro, P. M.

A. Bagolini, L. Pakula, T. L. M. Pham, P. J. French, and P. M. Sarro, “Polyimide sacrificial layer and novel materials for post-processing surface micromachining,” J. Micromech. Microeng. 12, 385–389 (2002).
[CrossRef]

Smith, S.

J. A. Mason, S. Smith, and D. Wasserman, “Strong absorption and selective thermal emission from a midinfrared metamaterial,” Appl. Phys. Lett. 98, 241105 (2011).
[CrossRef]

Sohn, Y. S.

S. W. Han, J. W. Kim, Y. S. Sohn, and D. P. Neikirk, “Design of infrared wavelength-selective microbolometers using planar multimode detectors,” Electron. Lett. 40, 1410–1411 (2004).
[CrossRef]

Starr, A. F.

X. Liu, T. Starr, A. F. Starr, and W. J. Padilla, “Infrared spatial; and frequency selective metamaterial with near-unity absorbance,” Phys. Rev. Lett. 104, 207403 (2010).
[CrossRef]

Starr, T.

X. Liu, T. Starr, A. F. Starr, and W. J. Padilla, “Infrared spatial; and frequency selective metamaterial with near-unity absorbance,” Phys. Rev. Lett. 104, 207403 (2010).
[CrossRef]

Talghader, J. J.

Tidrow, M. Z.

S. D. Gunapala, S. V. Bandara, J. K. Liu, J. M. Mumolo, C. J. Hill, S. B. Rafol, D. Salazar, J. Woollaway, P. D. LeVan, and M. Z. Tidrow, “Towards dualband megapixel QWIP focal plane arrays,” Infrared Phys. Technol. 50, 217–226 (2007).
[CrossRef]

Wang, Y.

Wasserman, D.

J. A. Mason, S. Smith, and D. Wasserman, “Strong absorption and selective thermal emission from a midinfrared metamaterial,” Appl. Phys. Lett. 98, 241105 (2011).
[CrossRef]

Wood, R. A.

R. A. Wood, “Uncooled thermal imaging with monolithic silicon focal planes,” Proc. SPIE 2020, 322–329 (1993).
[CrossRef]

Woollaway, J.

S. D. Gunapala, S. V. Bandara, J. K. Liu, J. M. Mumolo, C. J. Hill, S. B. Rafol, D. Salazar, J. Woollaway, P. D. LeVan, and M. Z. Tidrow, “Towards dualband megapixel QWIP focal plane arrays,” Infrared Phys. Technol. 50, 217–226 (2007).
[CrossRef]

Ye, Z.

Z. Ye, J. C. Campbell, Z. Chen, E.-T. Kim, and A. Madhukar, “A normal-incidence InAs self-assembled quantum-dot infrared photodetectors with a high detectivity,” IEEE J. Quantum Electron. 38, 1234–1237 (2002).
[CrossRef]

Appl. Phys. Lett. (1)

J. A. Mason, S. Smith, and D. Wasserman, “Strong absorption and selective thermal emission from a midinfrared metamaterial,” Appl. Phys. Lett. 98, 241105 (2011).
[CrossRef]

Electron. Lett. (1)

S. W. Han, J. W. Kim, Y. S. Sohn, and D. P. Neikirk, “Design of infrared wavelength-selective microbolometers using planar multimode detectors,” Electron. Lett. 40, 1410–1411 (2004).
[CrossRef]

IEEE J. Quantum Electron. (1)

Z. Ye, J. C. Campbell, Z. Chen, E.-T. Kim, and A. Madhukar, “A normal-incidence InAs self-assembled quantum-dot infrared photodetectors with a high detectivity,” IEEE J. Quantum Electron. 38, 1234–1237 (2002).
[CrossRef]

Infrared Phys. Technol. (1)

S. D. Gunapala, S. V. Bandara, J. K. Liu, J. M. Mumolo, C. J. Hill, S. B. Rafol, D. Salazar, J. Woollaway, P. D. LeVan, and M. Z. Tidrow, “Towards dualband megapixel QWIP focal plane arrays,” Infrared Phys. Technol. 50, 217–226 (2007).
[CrossRef]

J. Micromech. Microeng. (1)

A. Bagolini, L. Pakula, T. L. M. Pham, P. J. French, and P. M. Sarro, “Polyimide sacrificial layer and novel materials for post-processing surface micromachining,” J. Micromech. Microeng. 12, 385–389 (2002).
[CrossRef]

Opt. Lett. (2)

Phys. Rev. Lett. (1)

X. Liu, T. Starr, A. F. Starr, and W. J. Padilla, “Infrared spatial; and frequency selective metamaterial with near-unity absorbance,” Phys. Rev. Lett. 104, 207403 (2010).
[CrossRef]

Phys. Status Solidi A (1)

M. K. Gunde and M. Macek, “Infrared optical constants and dielectric response functions of silicon nitride and oxynitride films,” Phys. Status Solidi A 183, 439–449 (2001).
[CrossRef]

Proc. SPIE (2)

J.-Y. Jung, J. Y. Park, and D. P. Neikirk, “Wavelength-selective infrared detectors based on cross patterned resistive sheets,” Proc. SPIE 7298, 72980L (2009).
[CrossRef]

R. A. Wood, “Uncooled thermal imaging with monolithic silicon focal planes,” Proc. SPIE 2020, 322–329 (1993).
[CrossRef]

Other (4)

B. E. Cole, “Microstructure design for high IR sensitivity,” U. S. patent5,286,976 (15February1994).

E. D. Palik, Handbook of Optical Constants of Solids (Academic, 1985).

D. M. Pozar, Microwave Engineering (Addison-Wesley, 1993).

H. Hara, N. Kishi, and H. Iwaoka, “Silicon bolometer and micro variable infrared filter for CO2 measurement,” in Proceedings of IEEE Conference on Optical MEMS (IEEE, 2000), pp. 139–140.

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Figures (8)

Fig. 1.
Fig. 1.

(a) Configuration of dielectric-coated Salisbury screen (DSS) and design parameters. (b) Calculated absorption spectral responses for GA-optimized design; the peaks of absorption curves are as follows: at wavelength 8 μm (blue dashed) with dc sheet resistance Rs=444Ω/, thickness of upper dielectric layer d1=2.1μmλc/n, thickness of dielectric support layer d2=0.5μm(λc/n)/4, and air-gap thickness d3=3.9μmλc/2; at wavelength 10 μm (black solid) with dc sheet resistance Rs=459Ω/, thickness of upper dielectric layer d1=2.5μmλc/n, thickness of dielectric support layer d2=0.6μm(λc/n)/4, and air-gap thickness d3=5μmλc/2; at wavelength 12 μm (red dotted) with dc sheet resistance Rs=535Ω/, thickness of upper dielectric layer d1=1.6μm(λc/n)/2, thickness of dielectric support layer d2=0.7μm(λc/n)/4, and air-gap thickness d3=6μmλc/2.

Fig. 2.
Fig. 2.

Configuration of lower thermal mass structure design parameters and a SEM image of lower thermal mass structure.

Fig. 3.
Fig. 3.

(a) Comparison of calculated absorption spectral responses for DSS with d1λc/n (blue dashed), DSS with d1(λc/n)/2 (red dotted), and a lower thermal mass structure with only a dielectric layer below the absorber d10 (black solid). (b) Three colors centered at 8, 10, and 12 μm wavelength design for lower thermal mass structure.

Fig. 4.
Fig. 4.

Calculated absorption spectral responses for air-gap-tunable structure with a fixed thickness (0.625 μm) Ge dielectric layer below the absorber; the peaks of absorption curves are as follows: at wavelength 10 μm when air-gap thickness d2=5.0μm (black solid curve), at wavelength 8 μm when air-gap thickness d2= 3 .9 μm (blue dashed), at wavelength 9 μm when air-gap thickness d2= 4 .5μm (red dotted), at wavelength 11 μm when air-gap thickness d2= 5 .5μm (magenta dashed–dotted–dotted), and at wavelength 12 μm when air-gap thickness d2=6.0μm (green dashed–dotted)

Fig. 5.
Fig. 5.

Spectral responses of FTIR-microscope-measured absorption data (black solid) for modified DSS with thickness of Ge d1=0.7μm, air-gap thickness d2=4.9μm, and Cr absorber layer (Rs=400Ω/) compared to plane wave calculations for the same structure with three different sheet resistances: dc sheet resistance Rs=400Ω/ (blue dashed), dc sheet resistance Rs=100Ω/ (red dotted), and dc sheet resistance Rs=3000Ω/ (green dashed–dotted).

Fig. 6.
Fig. 6.

(a) Comparison of spectral responses of FTIR-microscope-measured absorption data (red curve) for Ge-layered Salisbury screen with a Ge thickness of 0.62 μm and a Cr thickness of 18 nm and plane wave calculations for Ge-layered Salisbury screen with three different sheet resistances: dc sheet resistance Rs=400Ω/ (black solid), dc sheet resistance Rs=100Ω/ (blue dashed), and dc sheet resistance Rs=2800Ω/ (green dashed–dotted). (b) Configuration of Ge-layered Salisbury screen. The inset shows configuration of Ge-layered Salisbury Screen.

Fig. 7.
Fig. 7.

(a) Spectral responses of FTIR-microscope-measured absorption data (black solid) for modified DSS with thickness of Ge d1=0.7μm, air-gap thickness d2=4.9μm, and Cr absorber layer (Rs=400Ω/) compared to plane wave calculated average of power absorption curve (red dotted) for five different air-gap thicknesses: power absorption divided by 5 for air-gap thickness d2=4.7μm (blue dashed), power absorption divided by 5 for air-gap thickness d2=4.8μm (green dashed–dotted), power absorption divided by 5 for air-gap thickness d2=4.9μm (yellow circular), power absorption divided by 5 for air-gap thickness d2=5μm (magenta dashed–dotted–dotted), and power absorption divided by 5 for air-gap thickness d2=5.1μm (cyan square). (b) Spectral responses of three different FTIR microscope field positions with 30μm×30μm field sizes on 150μm×150μm size pixel of device.

Fig. 8.
Fig. 8.

(a) Measured spectral responses showing the design rules for lower thermal mass structure, shown in Fig. 2(a), work well; fabricated device with (black solid) with thickness of Ge d1=0.5μm(λc/n)/4, air-gap thickness d2=3.8μmλc/2, and Cr absorber layer (Rs=400Ω/); fabricated device (red dotted) with thickness of Ge d1=0.6μm(λc/n)/4, air-gap thickness d2=4.8μmλc/2, and Cr absorber layer (Rs=400Ω/). (b) Spectral responses of measured data for varying air-gap thickness while the sheet resistance Rs=400Ω/ of Cr absorber layer and thickness of Ge d1=0.7μm are fixed; the power absorption curve for air-gap thickness d2=3.8μm (blue dashed), the power absorption curve for air-gap thickness d2=4.8μm (red dotted), and the power absorption curve for air-gap thickness d2=5.6μm (black solid).

Tables (2)

Tables Icon

Table 1. Specific Designs Yielding Responses Given in Fig. 1(b)

Tables Icon

Table 2. Specific Designs Yielding Responses Given in Fig. 3(b)

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