Array Detectors

1. Array Detectors S W McKnight and C A DiMarzio

2. Focal Plane Arrays

3. Imaging Systems H R Runciman, Thermal Imaging, CRC Press

4. Scanning vs. Staring Arrays • Scanning Systems • Point detector or linear array with scanning optics • Less complicated detector • Calibration easier • Scanning system expensive, fragile • Fast detector • Staring Arrays • Multiple detectors elements to capture pixels of image • Less complicated optics (lighter, smaller, no moving parts) • Longer integration time to increase sensitivity • Need multiplexer for signal read-out • Charge-Coupled Devices (CCD’s) • Charge transfer and collection • Easier processing, less interconnects • CMOS • Individually addressed and processed pixels • Less power • No loss in tranfer

5. S, Source G, Gate D, Drain n+ n+ SiO2 Insulator 20-100mm Channel: 2 to 500 mm into page P-Type Material NMOS B, Body N-Channel FET Structure Metal-Oxide-Semiconductor Channel Length 1 to 10 mm

6. Energy Band Picture of MOSFET(No Bias—Flatband) E Ec Ef Ev Metal (Al or Poly-Si) Oxide (SiO2) Semiconductor (p-Si) z

7. Energy Band Picture of MOSFET(Positive Gate Bias) E Ec Фb2 Ef Va Фb1 Ev Metal (Al or Poly-Si) Oxide (SiO2) Semiconductor (p-Si) z

8. MOSFET Carrier Reconfiguration (Depletion Bias) E Фb2 Ec Ef Va Фb1 Ev Depletion Region Oxide (SiO2) Metal (Al or Poly-Si) Semiconductor (p-Si) z

9. Creation of Depletion Layer and Inversion Channel • Depletion layer forms within 1μs after bias is applied • Inversion channel created by thermally generated carriers in ~ 1 s • For times short compared to 1 s, non-equilibrium situation with depletion region and empty channel. • Carriers created by optical absorption or external injection can be stored in well for many ms.

10. Carrier Injection Current Injection Ec Optical Injection E Vo-Vi Ef Va>Vt Ev Depletion Region Ef Semiconductor (p-Si) Oxide (SiO2) Metal (Al or Poly-Si) z

11. Charge-Coupled Device (CCD) G S S D D B B ~10 mm X nRows Channel Length 1 to 10 mm

12. Charge Transfer in CCD J Allison, Electronic Engineering Semiconductors and Devices, McGraw-Hill

13. Streetman & Banerjee, Solid State Electronic Devices, Prentice-Hall

14. Focal Plane Arrays • Monolithic Technology • Detector and read-out CCD on same chip • Parallel processing (lower cost) • Improved ruggedness • Lower performance • Lower yield • Hybrid Technology • Detector and read-out fabricated separately and bonded • Single-device processing (more expensive) • Thermal mismatch • Choice of material for better performance • HgCdTe for IR detector • Silicon for CCD

15. Hybrid Technology H R Runciman, Thermal Imaging, CRC Press

16. Hybrid Focal Plane Array J L Miller, Principles of Infrared Technology, Van Norstrand Reinhold

17. Array Interconnects J L Miller, Principles of Infrared Technology, Van Norstrand Reinhold

18. Platinum-Silicide Schottky Detectors EB~0.22 eV ↔ λ=5.6 μ Si PtSi hν Streetman & Banerjee, Solid State Electronic Devices, Prentice-Hall

19. PtSi Array Detectors • Low quantum efficiency (~1%) • Mid-Wave IR detection (1-5μ) • Long integration time (~1/60 s) • Good sensitivity ~0.05o C • Compatible with Si technology

20. Infrared Night Imaging Sierra Pacific Infrared, Inc.

21. Infrared Night Imaging (2:15 AM) Sierra Pacific Infrared, Inc.

22. Infrared Imaging—Circuit Hot Spot Sierra Pacific Infrared, Inc.

23. Infrared Imaging—Water Damage in Ceiling Sierra Pacific Infrared, Inc.

24. Infrared Imaging—Tank Fluid Level Sierra Pacific Infrared, Inc.

25. Infrared Imaging--- Building Energy Efficiency Sierra Pacific Infrared, Inc.

26. Infrared Imaging—Building Energy Efficiency Sierra Pacific Infrared, Inc.

27. Infrared Imaging—Biology Sierra Pacific Infrared, Inc.

28. Infrared Imaging—Power Line Faults Sierra Pacific Infrared, Inc.

29. Infrared Medical Imaging—Patient Recovering from Spinal Surgery Sierra Pacific Infrared, Inc.