Browsing by Author "Banzet, M."
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Item Open Access 1/f Noise characteristics of SEJ Y-Ba-Cu-O Rf-SQUIDs on LaAlO3 substrate and the step structure, film, and temperature dependence(IEEE, 2001-03) Fardmanesh, M.; Schubert, J.; Akram, R.; Bick, M.; Zhang, Y.; Banzet, M.; Zander, W.; Krause, H. J.; Burkhart, H.; Schilling, M.Step edge junction (SEJ) rf-SQUID magnetometers and gradiometers were fabricated using PLD Y-Ea-Cu-0 films on LaA10,(100) and SrTi0,(100) substrates. Effects of different step structure and the film properties on the yield, optimal operating temperature, and the l/f noise of the SQUIDs were investigated. The step structure was controlled using various IBE processes. The devices on LaAIO, showed higher sensitivity to the step structure compared to those on SrTiO,. This was due to re-deposition of substrate material at the steps prepared using the conventional IBE process resulting in a very low yield of unstable SQUIDs. High yield of low l/f noise stable SQUIDs was obtained on LaAIO, substrates with sharp steps prepared using an optimized IBE process. A typical l/f noise corner frequency of about lOHz at 77K with two major temperature dependencies was obtained. The temperature dependencies of the l/f noise could be correlated to the junction and the film of washer area of the SQUIDS. The white noise of our devices showed a dependency mainly on the amplitude of the flux to voltage transfer function signal. The operating temperature range of the SQUIDs could be controlled by the step structure and narrowed when the optimal operating temperature range was increased. All the measured junctions of our devices on the modified steps showed RSJ type behavior with a moderate decrease of the R, versus temperature.Item Open Access Analysis of electrical characteristics and magnetic field dependences of YBCO step edge and bicrystal grain boundary junctions for rf-SQUID applications(Institute of Physics, 2004) Fardmanesh, M.; Schubert, J.; Akram, R.; Bick, M.; Banzet, M.; Zander, W.; Zhang, Y.; Krause, H-J.The dc characteristics and magnetic field dependences of Y-Ba-Cu-O bicrystal grain boundary junctions (BGBJs) and step edge junctions (SEJs) were investigated for fabrication of rf-SQUIDs. Test junctions with up to 8 μm widths as well as the junctions of the two types of junction-based rf-SQUID were studied. The SEJs typically showed lower Jc and higher ρN as compared to the BGBJs, resulting in close IcRN products. All the BGBJs showed classical field dependent Ic following their junction width, resembling Fraunhofer patterns. The field sensitivity of the BGBJs' Uc led to low yield submicron BGBJ rf-SQUIDs partially impaired by the Earth's magnetic field. Two major behaviours of low and high field dependences of Ic were observed for the SEJs. Only the low field-sensitive SEJs resulted in micron size junction rf-SQUIDs not impaired by the Earth's magnetic field. The low field-sensitive SEJs led to low I/f noise magnetically stable rf-SQUIDs appropriate for applications in unshielded environments at 77 K.Item Open Access Analytical modelling of the interpixel thermal crosstalk in superconducting edge-transition bolometer arrays(Institute of Physics Publishing Ltd., 2006) Bozbey, A.; Fardmanesh, M.; Schubert, J.; Banzet, M.We present an analytical thermal model to explain the crosstalk in YBCO edge-transition bolometer arrays. The verification of the model was tested on sample array devices made of 200 and 400 nm YBCO films on LaAlO3 and SrTiO3 substrates. The model presented was able to explain the effects of the various physical parameters of the devices, such as the film thickness, operating temperature, and the device separation, which cause different response behaviours based on the variation of the related thermal crosstalk characteristics. In addition, the model is valid above the crosstalk-free modulation frequencies, where the effects of the thermal crosstalk on the response of the devices are negligible.Item Open Access Dependence of the substrate structure and the film growth at the junction of YBCO SEJ rf-SQUIDs on the IBE process and effects on the SQUID's characteristics(Elsevier, 2002) Fardmanesh, Mehdi; Schubert, J.; Akram, Rizwan; Banzet, M.; Zander, W.; Zhang, Y.; Schilling, M.; Krause, H-J.Step edge junction (SEJ) rf-SQUIDs were made of 200 nm thick YBCO films on LaAlO3(100) substrates using pulsed laser deposition technique. The steps on the substrates were developed using a combination of stationary and rotating angled argon ion beams with different beam energies and intensities. While sharp clean steps with heights up to 300 nm were obtained on the substrates using the combinatorial ion beam etching (IBE) process, very shallow ramp-type surfaces were found developing on the bottom of the trench, close to the steps. The ramp-type surfaces were found to be a source of hole-type defects in the films grown at the step edges. High quality films could be obtained on the flat regions away from the steps. Higher defect densities in the films close to the SEJs resulted in devices with higher 1/f noise and wider spread of the junction parameters. The 1/f noise of such devices increased with decreasing temperature. High quality films on sharp clean steps with flat substrate surfaces, developed using optimized combinatorial IBE process, resulted in higher yield of low 1/f noise SQUIDs. The Ic of the junctions and hence the working temperature of the SQUID could also be controlled by the junction width and the step height.Item Open Access Detectivity of YBCO transition edge bolometer: Modulation frequency, bias current and absorber effects(2008) Moftakharzadeh, A.; Kokabi, A.; Bozbey, A.; Ghods-Elahi, T.; Vesaghi, M.; Khorasani, S.; Banzet, M.; Schubert J.; Fardmanesh, M.Bolometric response and noise characteristics of YBCO superconductor transition edge IR detectors with relatively sharp transition and its resulting detectivity are investigated both theoretically and experimentally. The magnitude of response of a fabricated device was obtained for different bias currents and modulation frequencies. Also dependency of intrinsic noise of the device on the bias current in the vicinity of critical temperature was studied for various values of chopping frequencies. Using the measured and calculated bolometric response and noise characteristics, we found and analyzed the device detectivity versus frequency for different bias currents. The detectivity versus chopping frequency of the device did not decrease following the response strongly, due to the decrease of the noise at higher frequencies up to 1KHz, resulting in maximum detectivity around the modulation frequency of 100Hz. We also improved the detectivity of the device through the increase of the surface absorption by using a novel infrared absorber, which is made of a Copper-Carbon composite, coated in a low temperature process. Within the modulation frequency range studied in this investigation, comparison of device responsivity before and after the coating is also presented. © 2008 IOP Publishing Ltd.Item Open Access Effect of rf pumping frequency and rf input power on the flux to voltage transfer function of rf-SQUIDs(IEEE, 2007) Akram, Rizwan; Eker, Taylan; Bozbey, Ali; Fardmanesh, Mehdi; Schubert, J.; Banzet, M.We present the results on the correlation between the flux to voltage transfer function, Vspp, of the rf-SQUID and the rf-bias frequency as well as rf-bias power. Measurements were performed for different SQUID gradiometer samples chosen from the same batch or different batches. In order to have full control on the electronics parameters, an experimental rf-SQUID circuit was designed and implemented with an operation frequency of 600 MHz to 900 MHz. According to our findings, It has been observed that at any particular rf-bias power, Vspp vs. rf-bias frequency shows Sine-like behavior. We observed that the main lobe maxima exist close to the resonance frequency of the LC tank circuit and by changing only the power, amplitude of the main lobe and side lobes can be controlled. The Vspp vs. rf-bias power analysis shows that maximum of Vspp, strongly depends on the bias frequency. This can be correlated with the S11 parameter of LC tank circuit. We also observed that the devices from the same batch show main lobe maxima at different frequencies and/or power. Our SQUIDs with high working frequency gave their maxima at lower rf-bias powers leading to the need of having high frequency electronics with low bias power handling capabilities. It has also been observed that the SQUIDs from the same chip show similar characteristics regarding Vspp vs. frequency and power while the SQUIDs from different batches show completely different behavior for a fixed LC tank circuit configuration.Item Open Access Effect of the superconductivity transition on the response of YBCO edge transition bolometers(2003) Bozbey, Ali; Fardmanesh, Mehdi; Askerzade, I. N.; Banzet, M.; Schubert, J.Dependence of the phase and magnitude of the response of Y-Ba-Cu-O edge transition bolometers on the superconducting transition is studied. The responses of both large and small area devices were investigated and several anomalies are observed. The response of small area LaAlO3 devices considerably differed from that expected based on the dR/dT curve. This discrepancy is observed to be strongly dependent on the superconducting transition. Both the phase and magnitude/(dR/dT) of the response of the devices showed abrupt changes for below the Tc-onset when measured versus temperature, while the phase variation also showed strong dependence on the modulation frequency. We present the analysis and propose mechanisms responsible for the modulation frequency dependence of the response characteristics versus temperature, within the superconductivity transition region of the devices.Item Open Access Effects of the step structure on the yield, operating temperature, and the noise in step-edge Josephson junction rf-SQUID magnetometers and gradiometers(Elsevier, 2001) Fardmanesh, M.; Schubert, J.; Banzet, M.; Zander, W.; Zhang, Y.; Krause, H. J.Step-edge Josephson junction rf-SQUID magnetometers and gradiometers were made using YBCO films on LaAlO3(1 0 0) and SrTiO3(1 0 0) substrates. Designs with 150×150 μm2 loop and 3.6 mm diameter washer area for the magnetometers (230 pH), and 1.5 mm baseline and 1.5 mm diameter washer areas with a loop of 75×75 μm2 for the Gradiometers (490 pH) were used. Effects of the step structure on the yield, optimal operating temperature range, and the 1/f noise of the devices were investigated. The step structure was controlled using different ion beam etching (IBE) processes. The devices on LaAlO3 showed high sensitivity to the IBE parameters and the step structure while this was much less for the SrTiO3 substrate samples. This is mainly due to a considerable re-deposition of the substrate material on the step during the IBE process, in particular for LaAlO3, resulting in very low yield and high 1/f noise devices. The film structure at the step was also found to be essentially dependent on the step structure strongly affecting the 1/f noise of the devices. Using an optimized “combinational IBE” process, surface modified sharp steps were prepared resulting in high yield of low 1/f noise devices when combined with high quality YBCO film. A typical 1/f noise corner frequency of less than about 10 Hz with a white noise level of about 20 μΦo/Hz at liquid nitrogen temperature was obtained for these devices. The devices have shown stability over many thermal cycles and the time (over half a year since their fabrication) while kept at the room temperature environment. The operating temperature range of the devices was found to be controllable by the step depth and the film thickness for the steps.Item Open Access Electrical-contact-free readout of the response of superconductive bolometer arrays using thermal cross talk(Optical Society of America, 2006) Bozbey, A.; Fardmanesh, M.; Schubert, J.; Banzet, M.We utilized and investigated the unique dependence of the magnitude and phase of the response on thermal cross talk between bolometer pixels in an array to measure the response of the devices through fewer monitoring devices. We show the feasibility of the proposed readout technique by use of two source pixels in an array, as the image-mapping devices, and one optically shielded pixel as the readout device. While the sensing pixels were electrical-contact free, the readout device was current biased in 4-probe current-bias configuration. Both the phase and the magnitude of the response due to the cross talk in the array were found to be strongly dependent on the modulation frequency and the distance between the sensing and the readout pixels. A series of measurements were designed to extract the response of each single-sensing pixel. By combining the measured data, the response of individual pixels could be extracted through the interpolation of the mapped responses.Item Open Access Feasibility of electrical-contact free measurement of the response of superconductive bolometer arrays using the thermal crosstalk(2006) Bozbey, A.; Fardmanesh, M.; Schubert J.; Banzet, M.We utilized and investigated the unique dependence of the magnitude and phase of the response on the thermal crosstalk between bolometer pixels in an array to measure the response of the devices through fewer monitoring devices. In this study, we show the feasibility of the proposed read-out technique by use of two source pixels in an array, as the image-mapping devices, and one optically shielded pixel as the read-out device. While the sense pixels were electrical-contact free, the read-out device was current biased in 4-probe current-bias configuration. Both the phase and magnitude of the response due to the crosstalk in the array were found to be strongly dependent on the modulation frequency and the distance between the sense and read-out pixels. A series of measurements were designed to extract the response of each single sense-pixel. By combining the measured data, the response of individual pixels could be extracted through the interpolation of the mapped responses. © 2006 IOP Publishing Ltd.Item Open Access Front-end assembly optimization for high-Tcrf-SQUID based magnetic field imaging systems(2006) Akram, R.; Fardmanesh, M.; Schubert J.; Zander W.; Banzet, M.; Lomparski, D.; Schmidt, M.; Krause H.-J.We have investigated the rf-SQUID and its coupling to the tank circuit configurations to achieve an optimal front-end assembly for sensitive and high spatial resolution magnetic imaging systems. The investigation on the YBCO rf-SQUID coupling to the conventional LC tank circuits revealed that the coupling from the back of the SQUID substrate enhances the SQUID signal while facilitating the front-end assembly configuration. The optimal thickness of the substrate material between the SQUID and the tank circuit is 0.4mm for LaAlO3 resulting in an increase of SQUID flux-voltage transfer function signal, Vspp, of 1.5 times, and 0.5 mm for SrTiO3 with an increase of Vspp of 1.62 times compared to that of direct face to face couplings. For the rf-coupling with co-planar resonator, CPR, it has been found that the best configuration, in which a resonator is sandwiched between the SQUID substrate and resonator substrate, provides a Vspp about 3.4 times higher than the worse case where the resonator and the SQUID are coupled back to back. It has also been observed that the noise level does not depend considerably on whether a conventional LC tank circuit or a CPR is used. Though the use of resonator leads to a limitation of the achievable spatial resolution due to its flux-focusing characteristics. This resulted in favouring the use of the conventional tank circuits when considering the desired high spatial resolution. Effect of the YBCO flip-chip magnetic shielding of the SQUIDs in the back coupling with the LC-tank circuit configuration has also been investigated, in order to reduce the SQUID effective area to increase the spatial resolution and also to study the effect of the coupling of various types of the transformers to the SQUIDs. It is revealed that there is no considerable change in the flux-voltage transfer function signal level with respect to the effective shield area, while the lowest working temperature of the SQUIDs was slightly shifted higher by a couple of degrees depending on the shield area. © 2006 IOP Publishing Ltd.Item Open Access Investigation of bias current and modulation frequency dependences of detectivity of YBCO TES and the effects of coating of Cu-C composite absorber layer(2009) Moftakharzadeh, A.; Kokabi, A.; Bozbey, A.; Ghodselahi, T.; Vesaghi, M.A.; Khorasani, S.; Banzet, M.; Schubert J.; Fardmanesh, M.Bolometric response and noise characteristics of YBCO superconductor transition edge IR detectors with relatively sharp transition and its resulting detectivity are investigated both theoretically and experimentally. The magnitude of response of a fabricated device was obtained for different bias currents and modulation frequencies. Using the measured and calculated bolometric response and noise characteristics, we found and analyzed the device detectivity versus frequency for different bias currents. The detectivity versus chopping frequency of the device did not decrease following the response strongly, due to the decrease of the noise at higher frequencies up to 1 kHz, resulting in maximum detectivity around the modulation frequency of 100 Hz. We also improved the responsivity of the device through the increase of the surface absorption by using a novel infrared absorber, which is made of a copper-carbon composite, coated in a low-temperature process. Within the modulation frequency range studied in this paper, comparison of device detectivity before and after coating is also presented. © 2009 IEEE.Item Open Access Junction characteristics and magnetic field dependencies of low noise step edge junction Rf-SQUIDs for unshielded applications(IEEE, 2003-06) Fardmanesh, Mehdi; Schubert, J.; Akram, Rizwan; Bozbey, Ali; Bick, M.; Banzet, M.; Lomparski, D.; Zander, W.; Zhang, Y.; Krause, H-J.Step edge grain boundary (GB) junctions and rf-SQUIDs have been made using pulsed laser deposited Y-Ba-Cu-O films on crystalline LaAlO3 substrates. The steps were developed using various ion-beam etching processes resulting in sharp and ramp type step structures. Sharp step based GB junctions showed behavior of serial junctions with resistively shunted junction (RSJ)-like I-V characteristics. The ramped type step structures resulted in relatively high critical current, Ic, junctions and noisy SQUIDs. The sharp steps resulted in low noise rf-SQUIDs with a noise level below 140 fT/Hz12/ down to few Hz at 77 K while measured with conventional tank circuits. The Ic of the junctions and hence the operating temperature range of the SQUIDs made using sharp steps was controlled by both the step height and the junction widths. The junction properties of the SQUIDs were also characterized showing RSJ-like characteristics and magnetic field sensitivities correlated to that of the SQUIDs. Two major low and high background magnetic field sensitivities have been observed for our step edge junctions and the SQUIDs made on sharp steps. High quality step edge junctions with low magnetic field sensitivities made on clean sharp steps resulted in low 1/f noise rf-SQUIDs proper for applications in unshielded environment.Item Open Access Magnetic Field Behavior of YBCO step-edge Josephson junctions in rf-washer SQUIDs(IEEE, 2001-03) Bick, M.; Schubert, J.; Fardmanesh, M.; Panaitov, G.; Banzet, M.; Zander, W.; Zhang, Y.; Krause, H. J.he suppression of the critical current in YBCO Josephson junctions by the Earth's magnetic field strongly affects the operation of SQUIDs outside magnetic shielding. Commonly, one observes a modulation of the SQUID fluxvoltage transfer function amplitude, Vsq.pp, with a period of AB,, leading to an increased white flux noise level or unstable SQUID operation. Here, we report on the investigation of AB,., of rf-SQUID sensors based on step edge junctions (SEJ) operated in a flip chip configuration with coplanar resonators with integrated flux concentrators. To investigate the origin of the suppression of Vsq-pp, we opened the SQUID loop of some samples and measured the magnetic field dependence of the critical current I,(B) directly and compared it to VSqJB). It is shown that a junction width in the submicrometer scale is required for operation of the sensors in the Earth's magnetic field.Item Open Access Noise, junction characteristics, and magnetic field dependencies of bicrystal grain boundary junction Rf-SQUIDs(IEEE, 2003) Fardmanesh, Mehdi; Schubert, J.; Akram, Rizwan; Bick, M.; Banzet, M.; Zander, W.; Zhang, Y.; Krause, H-J.Bicrystal grain boundary (GB) Josephson junctions and rf-SQUID's were made of 200 nm thick PLD YBCO films on bi-crystal SrTiO3 substrates. The junction characteristics were studied to investigate optimal parameters in the rf-SQUID) layout designs and the limits imposed by the technology. The I c of 3 to 8 μm wide test junctions scaled with the junction widths, showing clear linear RSJ-like I-V characteristics at 77 K. All the junctions showed hysteretic RCSJ-like behavior at very low temperatures. Classical Josephson flux motion type (long junction) nonlinearity in I-V curves of all the junctions was also observed at lower temperatures with systematic dependence on the junction widths. Measurements of the magnetic field dependence of the Ic of the junctions resulted in junction width dependent well-defined Fraunhofer-pattern like characteristics. The obtained characteristics of the junctions led to feasible criteria for the rf-SQUID layouts with desired device characteristics. Rf-SQUID's were made using designs for optimal performance at 77 K while avoiding large superconducting weak links across the substrate GB. Devices with low noise characteristics and junction field sensitivities proper for operation in environmental background magnetic fields were obtained. A nonsystematic spread of optimal working temperature of the SQUID's were also observed which is associated to the spread of the junction parameters caused by the defects at the GB of substrates.Item Open Access The set-up of a high temperature superconductor radio-frequency SQUID microscope for magnetic nanoparticle detection(Institute of Physics Publishing Ltd., 2006) Schmidt, M.; Krause, H.-J.; Banzet, M.; Lomparski, D.; Schubert, J.; Zander, W.; Zhang, Y.; Akram, R.; Fardmanesh, M.SQUID (superconducting quantum interference device) microscopes are versatile instruments for biosensing applications, in particular for magnetic nanoparticle detection in immunoassay experiments. We are developing a SQUID microscope based on an HTS rf SQUID magnetometer sensor with a substrate resonator. For the cryogenic set-up, a configuration was realized in which the cryostat is continuously refilled and kept at a constant liquid nitrogen level by an isolated tube connection to a large liquid nitrogen reservoir. The SQUID is mounted on top of a sapphire finger, connected to the inner vessel of the stainless steel cryostat. The vacuum gap between the cold SQUID and room temperature sample is adjusted by the precise approach of a 50 νm thin sapphire window using a single fine thread wheel. We investigated possible sensing tip configurations and different sensor integration techniques in order to achieve an optimized design. A new scheme of coupling the rf SQUID from its back to a SrTiO3 substrate resonator was adopted for the purpose of minimization of the sensor-to-sample spacing. By SQUID substrate thinning and washer size reduction, the optimum coupling conditions for back coupling were determined for different rf SQUID magnetometers prepared on LaAlO3 and SrTiO3 substrates. The SQUID microscope system is characterized with respect to its spatial resolution and its magnetic field noise. The SQUID microscope instrument will be used for magnetic nanoparticle marker detection.Item Open Access Signal enhancement techniques for rf SQUID based magnetic imaging systems(Institute of Physics Publishing Ltd., 2006) Akram, R.; Fardmanesh, M.; Schubert, J.; Zander W.; Banzet, M.; Lomparski, D.; Schmidt, M.; Krause, H.-J.We have investigated the rf SQUID (radio-frequency superconducting quantum interference device) and its coupling to tank circuit configurations to achieve an optimal front-end assembly for sensitive and high spatial resolution magnetic imaging systems. The investigation of the YBCO rf SQUID coupling to the conventional LC tank circuits revealed that coupling from the back of the SQUID substrate enhances the SQUID signal while facilitating the front-end assembly configuration. The optimal thickness of the substrate material between the SQUID and the tank circuit is 0.4 mm for LaAlO3 resulting in an increase of the SQUID flux-voltage transfer function signal, Vspp, of 1.5 times, and 0.5 mm for SrTiO3 with an increase of V spp of 1.62 times compared to that for direct face to face couplings. For rf coupling with a coplanar resonator, it has been found that the best configuration, in which a resonator is sandwiched between the SQUID substrate and the resonator substrate, provides a Vspp about 3.4 times higher than that for the worse case where the resonator and the SQUID are coupled back to back. The use of a resonator leads to a limitation of the achievable spatial resolution due to its flux focusing characteristics. This resulted in a favouring of the use of the conventional tank circuits when considering the desired high spatial resolution. The effect of the YBCO flip chip magnetic shielding of the SQUIDs in the back-coupling with the LC tank circuit configuration has also been investigated, with a view to reducing the SQUID effective area to increase the spatial resolution and also for studying the effect of the coupling of various kinds of transformers to the SQUIDs. It is revealed that there is no very considerable change in the flux-voltage transfer function signal level with respect to the effective shield area, while the lowest working temperature of the SQUIDs was slightly shifted higher by a couple of degrees, depending on the shield area.Item Open Access Substrate and device pattern dependence of the thermal crosstalk in Y Ba2Cu 3O7−δ transition edge bolometer arrays(Institute of Electrical and Electronics Engineers, 2006-12) Bozbey, A.; Fardmanesh, M.; Schubert, J.; Banzet, M.Using YBa2CU3O7-delta (YBCO) thin films, pulsed laser deposited on 1-mm-thick LaAlO3 or SrTiO3 substrates, we made 4 x 1 pixel arrays of transition edge bolometers with separations between neighboring pixels ranging from 40 mu m to 170 mu m for testing purposes. We investigated the effects of the YBCO film thickness (200 and 400 nm), substrate material, and back-etching of the substrate, on the crosstalk between the pixels of the arrays. The investigation was based on the analysis of the voltage response of the de current biased bolometers versus the modulation frequency of a near-infrared laser source. We observed that the bolometer arrays made of 400-nm-thick films had less interpixel thermal crosstalk than the 200-nm-thick films. The effect of substrate thickness on the response of the pixels was investigated by up to 500 mu m back-etching of the substrates. The bolometers made on back-etched LaAlO3 substrates had anomalous crosstalk response behavior, which was effective at higher modulation frequencies. In addition, we present an analytical thermal model for explaining the observed effects of the thermal crosstalk on the response characteristics of the pixels of the arrays. We report the measured response and the anticipated thermal crosstalk of the characterized bolometers'. We describe the responses based on the thermal models and discrepancies from the model's predictions.Item Open Access Superconductivity transition dependence of the thermal crosstalk in YBa 2Cu 3O 7-x edge-transition bolometer arrays(Institute of Electrical and Electronics Engineers, 2006) Bozbey, A.; Fardmanesh, M.; Schubert, J.; Banzet, M.The effect of the superconductivity transition on the thermal crosstalk in YBa 2Cu 3O 7-x, edge-transition bolometer arrays is investigated for DC to midrange modulation frequency infrared radiation. The bolometers in the arrays were designed with various distances on SrTiO 3 (100) substrates. We have observed a change in the thermal crosstalk between neighbor devices through the superconductivity transition temperature range. Superconductivity transition dependence of the thermal coupling between the devices was measured by utilizing the thermal conductance measurement methods developed for the bulk material. The knee points in the magnitude of the response versus modulation frequency curves of the devices were also determined by illuminating one of the bolometers in the arrays and measuring the response of the neighbor devices. By using the knee frequency and the distance between the bolometers, the modulation frequency criterion for crosstalk-free response at the transition region in various array structures is found and the results of the thermal coupling measurements are further studied and presented here.