An active pixel sensor like an array of DEPFET (DEpleted P-channel Field Effect Transistor) pixels allows for very flexible operation modes and an adaptability of the sensor design to the specific ...needs of the scientific instrument objectives. For a very high time resolution at the order of one microsecond, a full parallel readout of all pixels is required. Every readout node needs to be connected to readout electronics separately. Furthermore, to preserve a good spectroscopic performance, the integration of a storage functionality into each pixel prevents the influence of events occurring during the readout process and provoking an incorrect energy information. The energy of such events is detected incorrectly and is not falsifiable with a subsequent analysis. An active pixel sensor based on a DEPFET with internal storage and wired for full parallel readout is in production and will be available for testing in the future. Alternatively, the ability of an active pixel sensor to be read out in window (region-of-interest readout) mode allows for the investigation of the behavior at high frame rates at the order of 100kHz for DEPFET devices with and without storage functionality.
A new generation of spectroscopic prototype DEPFET detectors provide a noise performance of 6 e−ENC rms with readout times shorter than 0.6 μs per pixel. This is enabled by the DEPFET pixels, which ...include a linear gate shaped transistor and the VERITAS readout ASIC, which is capable of operating the sensor in the source follower as well as in the drain current readout mode. The achievable frame rate does not depend only on the minimum processing time per pixel, but also on different possible readout schemes for the sensor array. In particular it is shown, that active DEPFET pixels can be binned together or can be operated in a window mode. The pixel binning is realized by controlling a cluster of DEPFET transistors together, in order to build one larger pixel. This results in a higher frame rate at the expense of spatial resolution and spectral performance. In the window mode solely a subset of pixels is read out while the remaining pixels are regularly cleared. The operated window provides a higher time resolution but spatial information is lost in the region outside the window. The measurements were done on 64×64 pixel detectors, which were operated either in the source follower or in drain current readout mode. In this paper we present studies and measurement results concerning the achievable time resolution of those detectors. A faster frame rate increases the fraction of misfit events—defined by signal charge collected during the readout—while decreasing the probability for pile-up events. Both effects are analyzed and compared with Monte Carlos simulations.
A new generation of spectroscopic X-ray DEPFET detectors has been produced in the course of the detector development for the Wide Field Imager (WFI) of Athena. These devices served to perform a ...detailed analysis of the noise composition, which was enabled by the development of appropriate test algorithms. A result of the analysis is the distinction of different components, which sum up to the total noise. In particular the contribution of shot noise, white noise and 1/f noise to the readout noise is determined as well as the signal noise caused by the generation of charge carriers. The resulting parametrization enables the adaptation and optimization of operation modes to given purposes. The studied prototype detectors included 64×64 pixels with a linear gate design and provided an excellent noise, below 1.6 e−ENC at a readout time faster than 10 μs/pixel and a temperature of -80 ˆC in rolling-shutter operation. This performance is enabled by an extended signal integration time. A further noise reduction is prevented by the signal noise, caused by charge carrier generation. In order to demonstrate the low noise properties of the DEPFET transistor, the measurement conditions were adapted and a noise of 0.95 e−ENC was measured at the expense of the sensor size—by operating only parts of the sensor in window mode—and dynamic range—by using the Al Kα line at about 1.49 keV for calibration.
The challenging demands of recent experiments in X-ray astrophysics promoted the development of DEPFET detectors. Their excellent performance is based on an intrinsic signal amplification, which is ...implemented for each active pixel. Most recently, prototypes of spectroscopic X-ray DEPFETs were investigated for the Wide Field Imager of ESA's next X-ray telescope Athena. For this reason, a dedicated prototype production of DEPFET sensors, comprising different technology options was fabricated and assembled to detector modules. In this paper we compared different sensor technology options and studied the spectroscopic performance on 64×64 pixel detectors. The sensors feature an identical layout but were taken from different wafers, which undergo specific manufacturing processes. These processes concern the thickness of the oxide underneath the transistor gate, the etching of the transistor gate and different surface implantations. Each process is correlated to the investigated properties of the corresponding detectors, which makes the detector best suited for specific applications. In particular DEPFET properties, concerning the clear behaviour, short channel effects or charge amplification are analysed. The studies are complemented by results of spectral measurements and electrical characterization.
To maintain a good spectral performance even at high readout speeds, active pixel sensors like the DEPFET need to be equipped with a storage functionality. Enhancing the frame rate to its limit—the ...readout time per pixel itself—the charge collection and the readout need to be separated spatially to avoid a significant degradation of the spectral performance. One implementation of a storage concept is the Infinipix DEPFET. The most promising Infinipix variant was investigated in greater detail to study the spectral performance for an array of 32×32 pixels. This includes the characterization of the temperature dependence and the contributions of the different noise components. With an optimal set of temperature and timing parameters, a spectrum taken with an iron-55 source was analyzed with high statistics and the energy response for different X-ray photon energies was evaluated.
The demanding requirements on large area silicon detectors of recent experiments in X-ray astrophysics promoted the development of DEPFET (depleted field effect transistor) active pixel sensors. ...Those sensors provide an excellent time resolution and noise behavior due to an intrinsic signal amplification, implemented for each pixel. A new generation of spectroscopic prototype X-ray detectors was recently developed for the Wide Field Imager of ESA's (European space agency) next X-ray observatory Athena. For this reason, a dedicated prototype production of DEPFET sensors, comprising different fabrication technologies, pixel layouts and readout modes was fabricated and assembled to detector modules. In this paper we compare different layout options and study their impact on the spectroscopic performance of 64×64 pixel detectors. The main difference concern the shape of the transistor gate and the size of the clear structures. Different gate dimensions determine the noise and gain, whereas the size of the clear and source regions mainly effects the charge collection and removal process. In particular DEPFET specific properties like the clear behaviour, short channel effects or the impact of the depletion state on the charge collection are analysed. The comparison of different layouts considers results of the spectral operation complemented by an electrical characterization.
Most modern particle physics experiments use silicon based sensors for their tracking systems. These sensors are able to detect particles generated in high energy collisions with high spatial ...resolution and therefore allow the precise reconstruction of particle tracks. So far only a few vendors were capable of producing silicon strip sensors with the quality needed in particle physics experiments. Together with the European-based semiconductor manufacturer Infineon Technologies AG (Infineon) the Institute of High Energy Physics of the Austrian Academy of Sciences (HEPHY) developed planar silicon strip sensors in p-on-n technology. This work presents the first results from a beam test of strip sensors manufactured by Infineon.
Qualification of a new supplier for silicon particle detectors Dragicevic, M.; Bartl, U.; Bergauer, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2013, Letnik:
732
Journal Article
Recenzirano
Most modern particle physics experiments use silicon based sensors for their tracking systems. These sensors are able to detect particles generated in high energy collisions with high spatial ...resolution and therefore allow the precise reconstruction of particle tracks. So far only a few vendors are capable of producing silicon strip sensors with the quality needed in particle physics experiments. Together with the European semiconductor manufacturer Infineon Technologies Austria AG the Institute of High Energy Physics of the Austrian Academy of Sciences developed planar silicon strip sensors in p-on-n technology. This paper presents the development, production and results from the electrical characterisation of the first sensors produced by Infineon.
Silicon detectors are often used in High Energy Physics (HEP) experiments as tracking and vertexing devices. Many scientific institutes are equipped with setups able to electrically characterize ...those detectors e.g. for quality assurance reasons. Such probe stations can be easily extended to measure resistivities and doping profiles in the bulk material and in doped regions by using the Spreading Resistance Probe (SRP) technique. After an introduction to the method, this paper describes how an existing probe station, that has been used for electrical measurements on strip detectors, has been modified to perform SRP measurements. The presented results prove that the method is reliable and capable of characterizing doping regions as thin as one micron. Beside profiling implants, SRP measurements have the potential to deliver the basis for investigations of bulk material defects in heavily irradiated samples.
PDF
