Geometrical enhancement of HgCdTe photoconductive detectors

Kinch, M. A.; Borrello, S.R.; Breazeale, B. H.; Simmons, A.

doi:10.1016/0020-0891(77)90106-3

Cited by 41 publications

(8 citation statements)

References 2 publications

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“…The basic idea of the overlap structure is to increase the effective lifetime of the excess carriers by providing a longer path along which they must drift or diffuse to reach the high recombination region at the contacts. At high bias fields, where drift is dominant over diffusion, it is clear that an enhancement of the effective lifetime is achieved for a fixed detector length [2][3][4].…”

Section: Theorymentioning

confidence: 99%

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Effect of fixed charges due to a passivant on the performance of the HgCdTe overlap structure

Bhan¹,

Gopal²,

Saxena³

2002

Semicond. Sci. Technol.

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We present calculations for the effect of fixed charge density (Q ss ) due to passivation on responsivity (R v ), noise (V n ) and specific detectivity (D * ) for the n-HgCdTe photoconductor (PC) overlap structure. The standard expressions of the PC overlap structure have been modified appropriately to include the effect of Q ss , present near the HgCdTe passivant interface, on the important parameters of the detector, namely resistance, responsivity, noise, detectivity and minority carrier lifetime. Our objective in this paper is to evaluate the tolerable limits of Q ss for given performance specifications. The symmetric and asymmetric PC overlap structures are studied and compared to standard non-overlap structures. Our results show that R v versus Q ss shows a peak in both symmetric and asymmetric overlap structures when Q ss is in the range of (2-3) × 10 11 cm −2 , and this optimum Q ss does not shift significantly when one moves from standard to overlap structures. Besides, this optimum Q ss is almost independent of bulk minority carrier lifetime (τ ). However, noise voltage versus Q ss shows a somewhat flat region for low Q ss , a sharply decreasing trend for high Q ss and a peak in the intermediate region. Furthermore, there is a stronger dependence on Q ss in overlap structures than in standard (non-overlap) structures. However, the parameter to be maximized, i.e. D * , shows that a value of Q ss of 2 × 10 11 cm −2 is optimum for both symmetric and asymmetric overlap structures, whereas a value of Q ss in the range of 2 × 10 11 to 1 × 10 12 cm −2 is optimum for standard structures. Additionally, we study the dependence of R v , V n and D * on detector length (a parameter increased for obtaining overlap design) and frequency for various values of Q ss in constant power mode. The predictions of the model fit reasonably well with the experimental data.

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Section: Theorymentioning

confidence: 99%

“…Due to the ever-increasing demands of higher resolution (necessitating smaller-sized detectors), the problem becomes severe when the detector length approaches drift length, and severely degrades the minority carrier lifetime (τ ). The solution to this problem was originally proposed by Kinch et al [2].…”

Section: Introductionmentioning

confidence: 99%

Effect of fixed charges due to a passivant on the performance of the HgCdTe overlap structure

Bhan¹,

Gopal²,

Saxena³

2002

Semicond. Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…The basic idea of overlap structure is to increase the effective lifetime of excess carriers by providing a longer path along which they must drift or diffuse to reach the high recombination region at the contacts. At high bias fields where drift is dominant over diffusion, it is clear that enhancement of effective lifetime is achieved for a fixed detector length [2][3][4].…”

Section: Detector: Overlap Structure Modelmentioning

confidence: 97%

“…The advantages of modified photoconductive (PC) detector structure called ''overlap structure'' are well known and discussed by several authors [1][2][3][4]. However, none of these authors included the contribution of shunt resistance due to passivantsemiconductor interface in their analysis.…”

Section: Introductionmentioning

confidence: 99%

Noise modeling of shunt resistance in HgCdTe photoconductor detectors

Bhan

Gopal

Saxena

et al. 2004

Infrared Physics & Technology

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“…Pixels with sensitive area size W×∆L = 50×50 µ m were either standard quadrant with length of semiconductor slab along bias current path equals to L = ∆ L = 50 µ m or with "shadowing" shield ( Fig. 4B) eliminating "sweep-out" effect of minority charge carriers 16,17 and with length of semiconductor slab along bias current path equals to L = 140 µ m. Devices were tested for spectral response, I-V curve, responsivity R V and low-frequency noise spectral density (NSD) at different background flux density (T bgr ≈ 300 K) at T op ≈ 290 -300 K and 78 K. Excess charge carriers were excited in sensitive structure by illumination through front graded-gap adjacent layer (Fig. 3).…”

Section: Metering Set-upmentioning

confidence: 99%

Variation of generation-recombination noise density with 300 K background flux in epitaxial LWIR Hg 1-x Cd x Te photoconductors having three-layer light absorbing configuration

Chekanova¹,

Drugova

Kurbatov³

et al. 2005

SPIE Proceedings

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Spectral density of "generation-recombination" noise voltage <δV 2 gr > ("g-r noise") in photoconductive Hg 1-x Cd x Te infrared radiation detectors with absorber n-Hg 1-x Cd x Te layer was calculated. Variations of <δV 2 gr > with doping level (n ≈ N d ), ambient background flux density (Q bgr , T bgr ≈ 300 K), electrical bias (V b /I b ) and pixel active area were analyzed. Spectral density of low-frequency noise as superposition of Flicker-noise "1/f", g-r noise resulting from fluctuations in generation-recombination rates of equilibrium (thermal) charge carriers <δV 2 gr,th > and excess charge carriers exited by background photons <δV 2 gr,bgr > and Johnson-Nyquist noise <δV 2 JN > were examined in small active area (30 µm × 30 µm and 50 µm × 50 µm) Hg 1-x Cd x Te photoconductors based on MBE-grown multi-layer structures. Noise measurements were performed on Long-Wave (LWIR) PC MCT detectors with responsivity peak wavelength 10 ≤ λ p ≤ 12 µ m at operating temperature T op ≈ 78 K. Tested PC MCT detectors show extremely low spectral density of excess. Measured dependencies of g-r noise voltage spectral density have confirmed BLIP mode of photoconductors up to FOV=10 0 where D*(λ p ) exceed 2×10 11 Jones.

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Geometrical enhancement of HgCdTe photoconductive detectors

Cited by 41 publications

References 2 publications

Effect of fixed charges due to a passivant on the performance of the HgCdTe overlap structure

Effect of fixed charges due to a passivant on the performance of the HgCdTe overlap structure

Noise modeling of shunt resistance in HgCdTe photoconductor detectors

Variation of generation-recombination noise density with 300 K background flux in epitaxial LWIR Hg 1-x Cd x Te photoconductors having three-layer light absorbing configuration

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