New ultra-light flexible large area thin film position sensitive detector based on amorphous silicon (original) (raw)
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Flexible large area thin film position sensitive detectors
Sensors and Actuators A: Physical, 2000
Large area thin film position sensitive detectors based on amorphous silicon technology have been prepared on polyimide substrates using the conventional plasma-enhanced chemical vapour deposition. The sensors have been characterised by spectral response, light intensity dependence and linearity measurements in a bent state in order to evaluate the properties in real working conditions. The Ž . obtained one-dimensional 1D position sensors with 10 mm width and 20 mm length present a non-linearity of "1% which are comparable to the ones produced on glass substrates. q
Production and characterization of large area flexible thin film position sensitive detectors
Thin Solid Films, 2001
Flexible large area thin film position sensitive detectors based on amorphous silicon technology were prepared on polyimide substrates using the conventional plasma enhanced chemical vapor deposition technique. The sensors were characterized by spectral response, illuminated I᎐V characteristics position detectability measurements and atomic force microscopy. The obtained one-dimensional position sensors, 5-mm wide and 60-mm long, presented a maximum spectral response at 600 nm, an open circuit voltage of 0.6 V and a position detectability with a correlation of 0.9989 associated to a S.D. of 1 = 10 y2 , comparable to those produced on glass substrates. ᮊ
Amorphous silicon position sensitive detectors applied to micropositioning
Journal of Non-crystalline Solids, 2006
The position of a 40 lm wide by 400 lm long cantilever in a microscope was detected by a 32 lines array of 1D amorphous silicon position sensitive detectors (PSD). The sensor was placed in the ocular used for the CCD camera of a microscope and the alignment, focusing and positioning of the cantilever was achieved using the X-Y-Z translation table of the microscope that has a micrometer resolution controller. In this work we present results concerning the micro positioning of a cantilever and its holding structure through the reflected light that is detected by 1D/3D psd and converted to an analog signal proportional to the movement. The signal given by the 32 sensor array was analyzed directly without any electronic readout system or data algorithm. The obtained results show a linear behavior of the photovoltage relating X and Y movement, a non-linearity less than 2% and spatial resolution of 600 lV/lm.
Large-Area Position-Sensitive Detector Based on Amorphous-Silicon Technology
Amorphous Silicon Technology-1993, 1993
We have developed a rectangular dual-axis large area Position Sensitive Detector (PSD), with 5 em x 5 em detection arca, based on PIN hydrogenated amorphous silicon (a-Si:H) technology, produced by Plasma Enhanced Chemical Vapor Deposition (PECVO). The metal. eontacts are located in the four edges of the detected area, two of them located on the back side of the ITO/PIN/Al structure and the others two loeated in the front side. The key factors of the detectors resolution and linearity are the thickness uniformity of the different layers, the geometry and the contacts location. Besides that, edge effects on the sensor's comer disturb the linearity of the detector. In this paper we present results concerning the linearity of the detector as well as its optoelectronic characteristics and the role of the i-Iayer thickness on the final sensor performances.
Micro Cantilever Movement Detection with an Amorphous Silicon Array of Position Sensitive Detectors
Sensors, 2010
The movement of a micro cantilever was detected via a self constructed portable data acquisition prototype system which integrates a linear array of 32 1D amorphous silicon position sensitive detectors (PSD). The system was mounted on a microscope using a metal structure platform and the movement of the 30 µm wide by 400 µm long cantilever was tracked by analyzing the signals acquired by the 32 sensor array electronic readout system and the relevant data algorithm. The obtained results show a linear behavior of the photocurrent relating X and Y movement, with a non-linearity of about 3%, a spatial resolution of less than 2µm along the lateral dimension of the sensor as well as of less than 3µmalong the perpendicular dimension of the sensor, when detecting just the micro-cantilever, and a spatial resolution of less than 1µm when detecting the holding structure.
Amorphous Silicon Position Sensitive Detector Array for Fast 3-D Object Profiling
IEEE Sensors Journal, 2000
The position of a 40 lm wide by 400 lm long cantilever in a microscope was detected by a 32 lines array of 1D amorphous silicon position sensitive detectors (PSD). The sensor was placed in the ocular used for the CCD camera of a microscope and the alignment, focusing and positioning of the cantilever was achieved using the X-Y-Z translation table of the microscope that has a micrometer resolution controller. In this work we present results concerning the micro positioning of a cantilever and its holding structure through the reflected light that is detected by 1D/3D psd and converted to an analog signal proportional to the movement. The signal given by the 32 sensor array was analyzed directly without any electronic readout system or data algorithm. The obtained results show a linear behavior of the photovoltage relating X and Y movement, a non-linearity less than 2% and spatial resolution of 600 lV/lm.
Performance of thin film silicon MEMS on flexible plastic substrates
Sensors and Actuators A-physical, 2008
The fabrication and characterization of thin film silicon MEMS microbridges on flexible polyethylene terephthalate substrates are described. Surface micromachining using an aluminum sacrificial layer and a maximum processing temperature of 110 • C was used for device fabrication. These microbridges are electrostatically actuated and their deflection at resonance and at low frequencies is measured optically. Quasi-DC deflection with a quadratic dependence of the actuation voltage is observed, and resonance frequencies up to 2 MHz and quality factors of around 500 are measured in vacuum. Bending measurements are performed by subjecting these devices to tensile and compressive strain. The low frequency response (bridge deflection as a function of the applied voltage) was measured in air before bending and after every bending step. Under tensile strain, 16.6% of the devices survive the maximum bending with a radius of curvature of 1 cm, equivalent to a tensile strain 1.25%. In contrast, for compressive strain, 50% of the devices survive the bending corresponding to a radius of curvature of −0.5 cm, equivalent to a compressive strain of −2.5%. Thin film silicon microresonators on flexible plastic substrates can withstand more compressive strain than tensile. (J.P. Conde). Biographies S.B. Patil received the PhD degree in metallurgical engineering and materials science from Indian Institute of Technology (IIT) Bombay, Mumbai, India in 2004. His PhD dissertation was on the amorphous silicon and its alloy thin films. He is currently a postdoctoral fellow at INESC Microsystems and Nanotechnologies, Lisbon, Portugal. His current research includes thin film microelectromechanical systems (MEMS) for DNA sensing and a hybrid MEMS-magnetoresistive sensor to detect weak magnetic field.
Journal of Non-Crystalline Solids, 2002
In this paper we present results concerning the optimisation of the electronic and mechanical properties presented by amorphous silicon (a-Si:H) thin films produced on polyimide (Kapton â VN) substrates with different thicknesses (25, 50 and 75 lm) by the plasma enhanced chemical vapour deposition (PECVD) technique. The purpose of this study is to obtain a low defect density as well as low residual stresses (specially at the interface) in order to provide good performances for large area (10 mm wide by 80 mm long) flexible position sensitive detectors. The electrical and optical properties presented by the films will be correlated to the sensor characteristics. The properties of samples have been measured by dark/photoconductivity, constant photocurrent measurements (CPM) and the results have been compared with films deposited on Corning 7059 glass substrates during the same run deposition. The residual stresses were measured using an active optical triangulation and angle resolved scattering. The preliminary results indicate that the thinner polymeric substrate with 25 lm presents the highest density of states, which is associated to the residual stresses and strains associated within the film. Ó
Flexible sensing systems based on polysilicon thin film transistors technology
Sensors and Actuators B: Chemical, 2013
Flexible sensors are gaining increasing interest in a number of applications, including biomedical, food control, domotics and robotics, having very light weight, robustness and low cost. In order to improve signal-to-noise ratio, integration of readout electronics is crucial and several technologies are available for the fabrication of thin film transistors (TFTs) based circuits on flexible substrates. Among these technologies, the low temperature polycrystalline silicon (LTPS) is particularly attractive, since LTPS TFTs show excellent electrical characteristics, good stability and offer the possibility to exploit CMOS architectures. The different aspects for the direct fabrication of LTPS TFTs on polymer substrates are reviewed and the specific fabrication process adopted on ultrathin polyimide substrates is described in some detail. Then, as examples of flexible sensing systems, we present both chemical and physical sensors integrated with LTPS TFTs frontend electronics. The present results can pave the way to advanced flexible sensing systems, where sensors and local signal conditioning circuits can be integrated on the same flexible substrate. (A. Pecora). in order to be easily hidden in specific places such as museum and galleries . Flexible smart sensors can be fully integrated with their front-end electronics, thus leading to flexible sensing systems, or conceived in disposable smart tags, exploiting the so-called multi-foil approach. However, in any case, a suitable flexible electronics must be mounted on these sensing systems to further boost the development of these applications and to push forward toward other emerging markets like robotics, aerospace, automotive, etc. Therefore, new requirements on front-end electronics and sensing systems are mandatory: the device performances must be competitive respect to the properties of conventional applications based on crystalline silicon, in terms of operating frequencies, electrical stability and low power consumption.