For the phonon-light technique employed in the CRESST experiment very sensitive light detectors are needed as only a small fraction of the energy of incident particles is detected as light. Following ...Neganov and Luke, the sensitivity can be improved by drifting the generated charge carriers in a semiconductor absorber by an applied electric field. For an efficient charge collection substrates with low trap densities are required. For this purpose and for electrical decoupling the TES is glued onto the drift device. Results from measurements with Neganov-Luke amplification using glued TES will be presented.
Traces of unintentionally introduced titanium into a 3 k
Ω
cm
float-zone epitaxial silicon at ultra low levels of
10
10
cm
−3
were found to be the origin of charge transfer loss in pn-CCDs. We ...identified and backtracked the titanium impurity. The full-depletion design of the pn-CCD, a thin entrance window at the back of the CCD and the low oxygen content of the float-zone material allow no common gettering step. Titanium is introduced into the wafer during the epitaxy process. This is independent of the reactor and the producer of the epitaxial silicon and seems to be a common epitaxy-related problem. To identify the impurity, electron emission rates of traps were measured by means of the CCD. The data were compared with emission rates of identical material obtained by standard-DLTS. The data agree well with literature data of the titanium acceptor level and the titanium donor level. An analysis of the capture cross section by means of the CCD gives a high electron capture cross section. This explains the strong effect of titanium even in very little concentrations in the pn-CCD. A two-dimensional distribution of the trap concentration was visualized on some wafers.
First operation of a pixel imaging matrix based on DEPFET pixels Fischer, P.; Kemmer, J.; Klein, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2000, Letnik:
451, Številka:
3
Journal Article
Recenzirano
In the DEPFET pixel concept the detected incident radiation is directly sensed and amplified by a JFET integrated in every pixel cell. While the DEPFET detector principle has already been ...demonstrated previously on single pixel structures, we present here the first successful operation of a large 32×32 DEPFET pixel matrix as an imaging device. The matrix has been exposed to 60 keV gamma rays of a
241
Am
source and has been scanned using an IR laser. The principle of operation as well as the charge collection in the structure and possible improvements are discussed.
In the DEPFET pixel concept, the absorbed radiation directly modulates the channel current of a p-JFET transistor being integrated into a fully depleted high ohmic silicon substrate in every pixel ...cell, offering very low noise operation at room temperature. Hence, DEPFET pixels open new possibilities in biomedical applications, but also have a potential in particle physics and astrophysics. Second prototype
50
μm×50
μm
single pixels as well as large (64×64) DEPFET matrices have been successfully produced and operated confirming the low noise behavior (12
e). Device studies as well as a full DEPFET pixel Bioscope system to be used in real-time digital autoradiography with excellent spatial and energy resolution for X-rays are presented.
The DEPFET pixel BIOSCOPE Neeser, W.; Bocker, M.; Buchholz, P. ...
IEEE transactions on nuclear science,
06/2000, Letnik:
47, Številka:
3
Journal Article
Recenzirano
The DEPFET pixel Bioscope system based on a DEPFET pixel matrix provides good spatial and energy resolution in real-time digital autoradiography. Due to its very low noise and a thin entrance window ...the online detection of tritium without vacuum or cooling is demonstrated for the first time. To achieve this milestone a p-channel junction field effect transistor on a fully depleted high ohmic silicon substrate (DEPFET) is used as unit cell for pixel detectors providing an excellent noise performance of 158 eV FWHM at 6 keV (12 e ENC) at room temperature (300 K). 64/spl times/64 DEPFET pixel matrices with square (50 /spl mu/m/spl times/50 /spl mu/m) or hexagonal (50 /spl mu/m/spl times/42 /spl mu/m) pixels have been developed and operated successfully. First measurements result in a homogeneous charge collection efficiency on the whole matrix area and a good linearity in the X-ray range from 5 keV to 60 keV. First images taken with the square and the hexagonal pixel matrices using an /sup 55/Fe-source as well as a 'proof of principle' experiment for online /sup 3/H-detection are presented and discussed.
A monolithic system with a silicon detector, front-end electronics and a BJT reset device to be operated in a charge amplifier and in continuous resetting mode is presented.
A fast qualitative method is described for evaluation of semiconductor parameters by analyzing both the capacitance/voltage (
C/V) and current/voltage (
I/V) characteristics of pn- or ...Schottky-diodes, which are fabricated on the material under investigation. The method is applied for measurement of recombination and generation lifetimes of minority charge carriers and for determination of doping profiles and distribution of active generation/recombination (G/R) centers after irradiation with Am-alpha particles and deep phosphorus implantation. Measurements on epitaxial silicon result in doping profiles and distributions of active impurities within the epi-layer.
The pn-CCD detector system is designed as a focal plane instrument for the European Photon Imaging Camera (EPIC) on the X-ray Multi Mirror mission (XMM) of the European Space Agency. This satellite ...will be launched by the end of this century. The sensitive area of the detector consists of a 6 × 6 cm
2 array of 12 pn-CCDs monolithically integrated on a single silicon wafer. The detector has been optimized for high-resolution X-ray spectroscopy between 100 eV and 15 keV with simultaneous good quantum efficiency for the investigation of faint objects. A fast readout achieves excellent time resolution for the observation of pulsed X-ray sources.
The relevant performance parameters reflecting the state of the detector development are presented. Energy resolution reaches the theoretical limits given by the Fano noise. Due to a thin entrance window and full depletion of the device the quantum efficiency is better than 80% over a wide energy range. Evidence for radiation hardness and background rejection capability will also be provided.
The spectral response of silicon X-ray detectors Eggert, T.; Boslau, O.; Kemmer, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2006, Letnik:
568, Številka:
1
Journal Article
Recenzirano
A discrete analytic calculation of the spectral response of silicon drift detectors for X-rays is presented. The results are compared with measurements at BESSY II using monochromatic synchrotron ...radiation in the energy range from 0.2 to 2
keV. All Gaussian features (main, escape, and Al fluorescence peak) as well as the background are included in the model. The peak intensities are calculated from energy dependent probability distributions. The non-Gaussian background is produced by charge-loss in the entrance window. The charge loss of energetic photo and Auger electrons and the diffusion of low-energy secondary electrons into the aluminum dead layer are considered. The secondary electrons disperse in a Gaussian charge distribution with the width
σ
sec
, which is the only free parameter of the model. All collected charge is summed up for every possible process and convoluted with electronic and Fano noise, yielding the energy distribution of the background. Its intensity is given by the probability of the process. This method generates all observed spectral background features using a single fundamental calculation scheme. It can, in principle, be applied to any type of semiconductor detector. The calculations are in very good agreement with the measurements.
Strip detectors covering radiation hardness and large-scale production ability are developed and produced for the ATLAS experiment at the Large Hadron Collider (LHC) at CERN (Switzerland). ...Capacitively coupled p
+n detectors (p-type strips on n-type substrate) were developed with implanted bias resistors in order to simplify the detector processing addressing the requirements of large-scale production. The detectors were irradiated with 24 GeV protons up to
3×10
14
cm
−2
in order to simulate a 10 years operation scenario at LHC. The presented static and signal measurements demonstrate the function of the device concept before and after irradiation.
