Non-Ohmic hopping conduction in doped germanium at<i>T</i>&lt;1 K

We summarize the fabrication, flight qualification, and dark performance of bolometers completed at the Jet Propulsion Laboratory for the High Frequency Instrument (HFI) of the joint ESA/NASA Herschel/ Planck mission to be launched in 2009. The HFI is a multicolor focal plane which consists of 52 bolometers operated at 100 mK. Each bolometer is mounted to a feedhorn-filter assembly which defines one of six frequency bands centered between 100-857 GHz. Four detectors in each of five bands from 143-857 GHz are coupled to both linear polarizations and thus measure the total intensity. In addition, eight detectors in each of four bands (100, 143, 217, and 353 GHz) couple only to a single linear polarization and thus provide measurements of the Stokes parameters, Q and U, as well as the total intensity. The measured noise equivalent power (NEP) of all detectors is at or below the background limit for the telescope and time constants are a few ms, short enough to resolve point sources as the 5 to 9 arc min beams move across the sky at 1 rpm.

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“…(1). This difference in fit quality for G > 200 pW=K is due, most likely, to nonohmic behavior of the NTD Ge [27][28][29].…”

Section: F Optical Response Timementioning

confidence: 99%

“…We find a best fit β ¼ 2:7 AE 0:36 for bolometers with G > 200 pW=K. The larger β ∼ 2:7 is likely influenced by nonthermal nonohmic effects [27][28][29]. Finally, we compute the bolometer responsivity S and NEP as a function of bias using Eqs.…”

Section: Static Thermal Propertiesmentioning

confidence: 99%

Initial test results on bolometers for the Planck high frequency instrument

et al. 2008

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“…~'32 The resistivity for variable range hopping versus electric field can be separated theoretically into three regions of low, high and very high electric fields. In low fields the resistance is expected to be nearly independent of the applied field--the "ohmic regime," though Grannan et al 9 found that this region was small or absent in some samples of neutron-transmutation doped (NTD) Ge at low temperatures. Low fields are defined as E < E~ = kT/eL where L is a length parameter related to the maximum hop length R with different values according to different authors, L=0.75R, ~z L=0.17R 33 or L=R~-/a, ~ where a is the radius of the wave function of the impurity states.…”

Section: V=vo+a(i-io)+b(i-io) 3 With A=ao(t-t) Ao>ob>o (6)mentioning

confidence: 97%

Epitaxial Si sensors at low temperatures: Non-linear effects

et al. 1997

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“…Nonlinear I-V characteristics for both charge transport mechanisms (VRH and fluctuation induced tunneling) can be observed. As far as R(T) dependencies in the low temperature range were approximated by Mott's law (1) for VRH conductivity, we assumed that nonlinearity of the I-V curves can be explained within the framework of classical theoretical models for hopping conductivity (Pollak & Riess, 1976;Grannan et al, 1992). According to these models, in the low electric fields, the conductivity is expected to be nearly independent of the applied electric field.…”

Section: Charge Transport In Swcnts Fibersmentioning

confidence: 99%

“…Low fields are defined as fields E<Ec, where Ec=k B T/el. In the region of high electric fields Ec<E<k B T/e (where  is a localization length), non-Ohmic VRH conductivity follows the formula (Pollak & Riess, 1976;Grannan et al, 1992):…”

Section: Charge Transport In Swcnts Fibersmentioning

confidence: 99%