Status of LWIR HgCdTe-on-Silicon FPA Technology

Carmody, M.; Pasko, J. G.; Edwall, D. D.; Piquette, E. C.; Kangas, Mike; Freeman, Simon E.; Arias, J.; Jacobs, R. N.; Mason, Whitney; Stoltz, A. J.; Chen, Y.; Dhar, Nibir K.

doi:10.1007/s11664-008-0434-3

Cited by 20 publications

(17 citation statements)

References 7 publications

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“…equipment is being carried out for MCT MBE growth on large in diameter (up to 6") (112) Si substrates. It was shown that MCT/Si can be used for fabrication of high quality photonic IR FPAs in a spectral range up to 10 μm [6]. The MCT MBE growth on (013) GaAs substrates [7] have been studied.…”

Section: Introductionmentioning

confidence: 99%

HgCdTe nanostructures on GaAs and Si substrate for IR and THz radiation detecting

Yakushev¹,

Варавин

Васильев

et al. 2012

J. Phys.: Conf. Ser.

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Abstract. All-round studies of heteroepitaxial HgCdTe nanostructures (NS) growth on GaAs and Si substrates by molecular beam epitaxy have been carried out. In case of Si substrate HgCdTe NS's is very perspectives for IR detectors because of equal thermal expention coefficient with silicon read-out circuits. The problems of HgCdTe conjugations with Si at epitaxy connected with large differences in lattice mismatch and differences in chemical bonding that leads to antiphased domains. We found that the precise formation of transition layer (2 nm in thickness between Si substrates and first ZnTe buffer layer leads to growth HgCdTe NS's without antiphrasis domains. V-defects and etch pits densities are equal to 10 3 cm -2 and 10 7 cm -2 respectively. The HgCdTe/Si were used for fabrication photovoltaic 640×512 MWIR focal plane arrays. The operability for 1/2 = 4.2 m (77К) was over 97%. The response (Sv) and NETD were as 1,5×10 9 V/W and less 20 mK respectively. We developed the precise growth of symmetric and antisymmetric HgTe QW. We found the following effects: the presence 2D electron gas with high mobilities over 5×10 5 cm/V×s in doped HgTe QW, the presence @D holes and electrons in undoped HgTe QW and high sensitivity to linear and circular polarized IR and THz radiation in 6 -400 m region.

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Section: Introductionmentioning

confidence: 99%

HgCdTe nanostructures on GaAs and Si substrate for IR and THz radiation detecting

Yakushev¹,

Варавин

Васильев

et al. 2012

J. Phys.: Conf. Ser.

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“…While high resolution IR imaging can meet these challenges, there is a considerable cost in terms of power, form factor, and finance, in part due to higher costs of IR detector materials and material processing challenges when constructing small pitch FPAs. Despite recent advances, [8][9][10] copious research funds continue to be spent on developing larger format arrays with small pitch. CS addresses the question of whether it is necessary to physically produce smaller sensors in order to achieve higher resolution.…”

Section: Introductionmentioning

confidence: 99%

Compressed sensing for practical optical imaging systems: a tutorial

2011

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Abstract. The emerging field of compressed sensing has potentially powerful implications for the design of optical imaging devices. In particular, compressed sensing theory suggests that one can recover a scene at a higher resolution than is dictated by the pitch of the focal plane array. This rather remarkable result comes with some important caveats however, especially when practical issues associated with physical implementation are taken into account. This tutorial discusses compressed sensing in the context of optical imaging devices, emphasizing the practical hurdles related to building such devices, and offering suggestions for overcoming these hurdles. Examples and analysis specifically related to infrared imaging highlight the challenges associated with large format focal plane arrays and how these challenges can be mitigated using compressed sensing ideas. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.3596602] Subject terms: compressed sensing; sampling; image reconstruction; inverse problems; computational imaging; infrared; coded aperture imaging; optimization.Paper 100978TR received Nov. 29, 2010; revised manuscript received May 8, 2011; accepted for publication May 12, 2011; published online Jul. 6, 2011. IntroductionThis tutorial describes new methods and computational imagers for increasing system resolution based on recently developed compressed sensing (CS, also referred to as compressive sampling) 1, 2 techniques. CS is a mathematical framework with several powerful theorems that provide insight into how a high resolution image can be inferred from a relatively small number of measurements using sophisticated computational methods. For example, in theory a 1 mega-pixel array could potentially be used to reconstruct a 4 mega-pixel image by projecting the desired high resolution image onto a set of low resolution measurements (via spatial light modulators, for instance) and then recovering the 4 mega-pixel scene through sparse signal reconstruction software. However, it is not immediately clear how to build a practical system that incorporates these theoretical concepts. This paper provides a tutorial on CS for optical engineers which focuses on 1. a brief overview of the main theoretical tenets of CS, 2. physical systems designed with CS theory in mind and the various tradeoffs associated with these systems, and 3. an overview of the state-of-the-art in sparse reconstruction algorithms used for CS image formation. There are several other tutorials on CS available in the literature which we highly recommend; 3-7 however, these papers do not address important technical issues related to optical systems, including a discussion of the tradeoffs associated with non-negativity, photon noise, and the practicality of implementation in real imaging systems.Although the CS theory and methods we describe in this paper can be applied to many general imaging systems, we concentrate on infrared (IR) technology as a specific example to highlight the challenges associated...

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“…[1][2][3][4][5][6][7][8] However, the goal of advancing this material technology to the long-wavelength (LWIR) regime has been hampered by the one to two orders of magnitude increase in dislocation density with respect to HgCdTe grown on lattice-matched bulk CdZnTe substrates. This deficiency in dislocation density has been shown to limit lifetimes, 9,10 lower mobility of carriers, 11 lead to larger dark currents in longwavelength detectors, 12,13 and ultimately reduce focal-plane array operability. 9,14 Current growth methods of HgCdTe/Si result in a dislocation density of mid 10 6 cm À2 to low 10 7 cm À2 .…”

Section: Introductionmentioning

confidence: 99%

“…This deficiency in dislocation density has been shown to limit lifetimes, 9,10 lower mobility of carriers, 11 lead to larger dark currents in longwavelength detectors, 12,13 and ultimately reduce focal-plane array operability. 9,14 Current growth methods of HgCdTe/Si result in a dislocation density of mid 10 6 cm À2 to low 10 7 cm À2 . It has been the goal of the HgCdTe community in the past several years to reduce this value significantly.…”

Section: Introductionmentioning

confidence: 99%

Dislocation Reduction of HgCdTe/Si Through Ex Situ Annealing

Brill

Farrell

Chen

et al. 2010

Journal of Elec Materi

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Current growth methods of HgCdTe/Cd(Se)Te/Si by molecular-beam epitaxy (MBE) result in a dislocation density of mid 10 6 cm À2 to low 10 7 cm À2 . Although the exact mechanism is unknown, it is well accepted that this high level of dislocation density leads to poorer long-wavelength infrared (LWIR) focal-plane array (FPA) performance, especially in terms of operability. We have conducted a detailed study of ex situ cycle annealing of HgCdTe/ Cd(Se)Te/Si material in order to reduce the total number of dislocations present in as-grown material. We have successfully and consistently shown a reduction of one half to one full order of magnitude in the number of dislocations as counted by etch pit density (EPD) methods. Additionally, we have observed a corresponding decrease in x-ray full-width at half-maximum (FWHM) of ex situ annealed HgCdTe/Si layers. Among all parameters studied, the total number of annealing cycles seems to have the greatest impact on dislocation reduction. Currently, we have obtained numerous HgCdTe/Si layers which have EPD values measuring $1 9 10 6 cm À2 after completion of thermal cycle annealing. Preliminary Hall measurements indicate that electrical characteristics of the material can be maintained.

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Status of LWIR HgCdTe-on-Silicon FPA Technology

Cited by 20 publications

References 7 publications

HgCdTe nanostructures on GaAs and Si substrate for IR and THz radiation detecting

HgCdTe nanostructures on GaAs and Si substrate for IR and THz radiation detecting

Compressed sensing for practical optical imaging systems: a tutorial

Dislocation Reduction of HgCdTe/Si Through Ex Situ Annealing

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