Production and characterization of large area flexible thin film position sensitive detectors (original) (raw)
Related papers
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
New ultra-light flexible large area thin film position sensitive detector based on amorphous silicon
Journal of Non-Crystalline Solids, 2000
In this paper we report on large area one dimensional (1D) amorphous silicon position sensors deposited on¯exible polymer foil substrate. The pin sensor structure was deposited by rf plasma enhanced chemical vapour deposition (PECVD). For the electrical and optical characterisation the sensors have been mounted on a convex holder with a 14mm radius-of-curvature, since the main goal of this work is to develop a¯exible position sensor to be incorporated in a micromotor in order to measure its angular velocity continuously. The obtained sensors present adequate performances concerning the position non-linearity (AE1% in 20 mm length), comparable to those fabricated on glass substrates. Ó
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
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.
Flexible a-Si:H Position-Sensitive Detectors
Proceedings of the IEEE, 2005
Flexible and large area (5 mm 2 80 mm with an active length of 70 mm) position-sensitive detectors (PSDs) deposited onto polymeric substrates (polyimide-Kapton VN) have been fabricated. The optimized structure presented is based on a heterojunction of amorphous silicon (a-Si : H)/ZnO : Al. The sensors were characterized by spectral response, photocurrent dependence as a function of light intensity, and position detection measurements. The set of data obtained on one-dimensional PSDs based on the heterojunction show excellent performances with a maximum spectral response of 0.12 A/W at 500 nm and a nonlinearity of 610% over 70-mm length. The produced sensors present a nonlinearity higher than those ones produced on glass substrates, due to the different thermal coefficients exhibited by the polymer and the a-Si : H film. In order to prove this behavior, it was measured the defect density obtained by the constant photocurrent method on a-Si : H thin films deposited on polymeric substrates and bent with different radii of curvature.
New insights on large area flexible position sensitive detectors
Journal of Non-Crystalline Solids, 2002
In this paper we present an improved version of large area ð5 mm  80 mmÞ flexible position sensitive detectors deposited on polyimide (Kapton â VN) substrates with 75 lm thickness, produced by plasma enhanced chemical vapor deposition (PECVD). The structures presented by the sensors are Kapton/ZnO:Al/(pin)a-Si:H/Al and the heterostructure Kapton/Cr/(in)a-Si:H/ZnO:Al. These sensors were characterized by spectral response, photocurrent dependence as a function of light intensity and position detectability measurements. The set of data obtained on one-dimensional position sensitive detectors based on the heterostructure show excellent performances with a maximum spectral response of 0.12 A/W at 500 nm and a non-linearity of AE10%. Ó
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.
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.
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.