Evaluation of 1/f noise in prospective IR imaging thin films

Basantani, Hitesh A.; John, David B. Saint; Podraza, Nikolas J.; Jackson, Thomas N.; Horn, Mark W.

doi:10.1117/12.2054652

Cited by 3 publications

(2 citation statements)

References 14 publications

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“…Hydrogenated amorphous silicon (a‐Si:H) and related thin films have been implemented in device applications, including absorbers in thin film solar cells, [ 11–21 ] passivation layers in wafer silicon photovoltaics, [ 22–28 ] and imaging layers in uncooled infrared (IR) sensing microbolometers. [ 29–37 ] The a‐Si:H network varies in terms of incorporated hydrogen content and bonding configuration, [ 23,26,38–41 ] the presence of nanoscale voids and vacancy structures, [ 38,39 ] and film stress [ 42 ] as deduced from experimental measurements. The formation of short and long filamentary structures, bond length distributions, and bond angle distributions has been identified through advanced computational modeling.…”

Section: Introductionmentioning

confidence: 99%

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Mean Free Path of Photoelectronic Excitations in Hydrogenated Amorphous Silicon and Silicon Germanium Alloy Semiconductors

Podraza

John

Collins

2021

Physica Status Solidi (b)

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Hydrogenated amorphous silicon germanium alloy (a‐Si1−x Ge x :H) films are prepared by plasma enhanced chemical vapor deposition (PECVD) and characterized by in situ real time spectroscopic ellipsometry (RTSE). From complex dielectric function spectra extracted, the broadening width energy (Γ) of the primary absorption feature centered near 3.7 eV is quantified using the Cody–Lorentz oscillator model. Mean free path length of photoelectronic excitations is calculated from Γ based on reasonable estimates for speed of electron–hole photoexcitations. A model is applied with excited state lifetime assumed to be limited by scattering from network disorder and provides a relative measure of short‐range order. The simple model applied is an extension of that widely used to characterize broadening of optical transitions in polycrystalline semiconductors. Decreases in mean free path of up to ∼30% occur with germanium. Relative increases in mean free path with increased hydrogen during PECVD a‐Si:H, a‐Si0.73Ge0.27:H, and a‐Si0.60Ge0.40:H occur from ∼5% to ∼8% and with hydrogen plasma treatment of a‐Si:H by ∼6%. Mean free path changes are tracked with thickness to provide short range order evolution and the effect of the underlying material. Mean free path of photoexcitations in electronic quality a‐Si1−x Ge x :H is estimated at ∼3.5 Å, on the same order as interatomic spacing.

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Section: Introductionmentioning

confidence: 99%

“…[ 12,13,15,17–20 ] Incorporation of either carbon or germanium into a‐Si:H also alters the film resistivity, temperature coefficient of resistance, and 1/ f noise, which impact microbolometer performance. [ 30–32,34–37 ]…”

Section: Introductionmentioning

confidence: 99%

Mean Free Path of Photoelectronic Excitations in Hydrogenated Amorphous Silicon and Silicon Germanium Alloy Semiconductors

Podraza

John

Collins

2021

Physica Status Solidi (b)

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Conductance fluctuations in hydrogenated amorphous germanium

Knauber

Eslamisaray

Kakalios

2021

Journal of Applied Physics

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Measurements of conductance fluctuations in undoped hydrogenated amorphous germanium (a-Ge:H) find power spectra that vary with inverse frequency (1/f) that are characterized by non-Gaussian statistics. The non-Gaussian aspect of the 1/f noise is reflected in (1) histograms of the noise power per octave that are described by lognormal distributions, (2) power-law second spectra, and (3) strong correlations of the noise power in frequency-space. In contrast, measurements of current fluctuations in polycrystalline germanium thin films find 1/f noise with Gaussian statistics. These results are discussed in terms of a model of filamentary conduction, where the filament structure and conductance in a-Ge:H are modulated by hydrogen motion.

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Dual band sensitivity enhancements of a VO_x microbolometer array using a patterned gold black absorber

et al. 2016

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Infrared-absorbing gold black has been selectively patterned onto the active surfaces of a vanadium-oxide-based infrared bolometer array. Patterning by metal lift-off relies on protection of the fragile gold black with an evaporated oxide, which preserves much of gold black's high absorptance. This patterned gold black also survives the dry-etch removal of the sacrificial polyimide used to fabricate the air-bridge bolometers. For our fabricated devices, infrared responsivity is improved 22% in the long-wave IR and 70% in the mid-wave IR by the gold black coating, with no significant change in detector noise, using a 300°C blackbody and 80 Hz chopping rate. The increase in the time constant caused by the additional mass of gold black is ∼15%.

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Evaluation of 1/f noise in prospective IR imaging thin films

Abstract: Vanadium oxide (

Cited by 3 publications

References 14 publications

Mean Free Path of Photoelectronic Excitations in Hydrogenated Amorphous Silicon and Silicon Germanium Alloy Semiconductors

Mean Free Path of Photoelectronic Excitations in Hydrogenated Amorphous Silicon and Silicon Germanium Alloy Semiconductors

Conductance fluctuations in hydrogenated amorphous germanium

Dual band sensitivity enhancements of a VO_x microbolometer array using a patterned gold black absorber

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