High performance focal plane array technologies from short to long wavelength infrared bands

Arslan, Yetkin
This thesis work covers the development of three different state of the art infrared sensor technologies: quantum well infrared photodetectors (QWIPs), HgCdTe sensors and extended InGaAs photodetectors. QWIP is the leading member of the quantum structure infrared photodetector family providing excellent uniformity and stability with field proven performance. The utilization of the InP/In0.48Ga0.52As multi-quantum well structure (instead of the standard AlGaAs/GaAs material system) for the implementation of large format (640x512 format, 25 µm pitch) long wavelength infrared (LWIR) QWIP focal plane arrays (FPAs) and the careful design of the detector structure yielded a quantum efficiency as high as 31% in the diffraction grating coupled FPA pixels, which is almost an order of magnitude larger than the pixel quantum efficiency of a standard AlGaAs/GaAs QWIP FPA. The noise equivalent temperature difference of the FPA with f/2 optics is 30 mK with an integration time as low as 1 ms at 67 K. Above 20% conversion efficiency of the FPA allows desirable thermal imaging with integration times as low as several hundred µs. The results demonstrate that the main limitations of the standard QWIP technology can be overcome through the utilization of alternative material systems and proper FPA processing techniques. HgCdTe is the material of choice for high-end infrared imaging systems, offering high flexibility and still unmatched performance. In this work, complete production cycles for photovoltaic HgCdTe focal plane arrays are developed starting from the molecular beam epitaxy (MBE) growth of the material. The dynamic resistance-area product of the developed LWIR HgCdTe FPA (~ 10 µm cut-off wavelength) pixels is as high as ~2000 Ω-cm2 at 78 K. The peak detectivity of the pixels is as high as 1.28x1011 cm√Hz/W with f/1 optics which is comparable to that of the best LWIR HgCdTe detectors with similar cut-off wavelength. We have also developed the procedures to implement a solid source (MBE) grown large format (640x512) extended short wavelength infrared (SWIR) In0.83Ga0.17As sensor with desirable performance at both pixel and FPA levels. The FPA pixels in the mesa structure grown in our laboratory on a graded AlInAs buffer layer with 2.65 µm 300 K cut-off wavelength exhibited 300 and 200 K peak detectivities as high as ~2.5x1010 and ~1x1012 cm√Hz/W which are both equivalent to the theoretical limits set by the Johnson noise of the detector. Dark current analysis of the pixels displayed no considerable tunneling component with the dark current being dominated by generation-recombination and shunt leakage mechanisms above 200 K up to a reverse bias voltage of 3 V. Moreover, the noise measurements displayed no 1/f noise in the FPA pixels. In spite of the large lattice mismatch, the FPA yielded very good response linearity, as well as impressively good responsivity nonuniformity and pixel operability of 5.5 % and 99.8 %, which are among the best results reported for extended InGaAs FPAs with similar cut-off wavelengths. These results demonstrate the feasibility of the InGaAs SWIR FPA technology with extended cut-off wavelengths as high as ~2.7 µm as an alternative to SWIR HgCdTe FPAs with higher production cost. .


Metamaterial based wideband infrared absorbers
Üstün, Kadir; Sayan, Gönül; Department of Electrical and Electronics Engineering (2017)
In this thesis, design and simulation of wideband metamaterial absorbers are investigated in the long wave infrared (LWIR) and the mid-wave infrared (MWIR) bands of the electromagnetic spectrum. Use of LWIR and MWIR bands in absorber design is especially important for critical applications including the design of thermal cameras and thermal emitters. Integration of metamaterial topologies into the absorber structures provides flexibilities in design to enhance the operation efficiency of these devices by in...
High performance HgCdTe photodetector desings via dark current suppression
Özer, Yiğit; Kocaman, Serdar; Department of Electrical and Electronics Engineering (2018)
This thesis work covers the numerical analysis and design of infrared photon detectors with a focus of HgCdTe based devices. An in-house numerical tool is utilized for the design and characterization process, where the Poisson, current and continuity equations are solved numerically with the high precision in electrical and optical properties. A high operating temperature alternative substrate mid-wave HgCdTe detector is designed benefiting from the generation-recombination dark current suppression. The adv...
Low-cost uncooled infrared detector arrays in standard CMOS
Eminoglu, S; Tanrikulu, MY; Akın, Tayfun (2003-04-25)
This paper reports the development of a low-cost 128 x 128 uncooled infrared focal plane array (FPA) based on suspended and thermally isolated CMOS p(+)-active/n-well diodes. The FPA is fabricated using a standard 0.35 mum CMOS process followed by simple post-CMOS bulk micromachining that does not require any critical lithography or complicated deposition steps; and therefore, the cost of the uncooled FPA is almost equal to the cost of the CMOS chip. The post-CMOS fabrication steps include an RIE etching to...
Development of high fill factor and high performance uncooled infrared detector pixels
Küçük, Şeniz Esra; Akın, Tayfun; Department of Electrical and Electronics Engineering (2011)
This thesis presents the design, fabrication and characterization of high performance and high fill factor surface micromachined uncooled infrared resistive microbolometer detectors which can be used in large format focal plane arrays (FPAs). The detector pixels, which have a pixel pitch of 25 μm, are designed and fabricated as two-level structures using the enhanced sandwich type resistor while the active material is selected as Yttrium Barium Copper Oxide (YBCO). First level of the pixel structure is allo...
The First Fabricated Dual-Band Uncooled Infrared Microbolometer Detector with a Tunable Micro-Mirror Structure
Keskin, Selcuk; Akın, Tayfun (2012-04-27)
This paper presents the first fabricated dual-band uncooled resistive infrared thermal microbolometer implemented with a resistive microbolometer and a tunable micro-mirror structure. Tunable reflective micro-mirrors are suspended underneath the suspended resistive microbolometers having a 35 mu m pixel pitch, and they are switched between two positions by the application of an electrostatic force for obtaining different responses in two wavelength infrared atmospheric windows, namely the 3-5 and 8-14 mu m,...
Citation Formats
Y. Arslan, “High performance focal plane array technologies from short to long wavelength infrared bands,” Ph.D. - Doctoral Program, Middle East Technical University, 2014.