Conditions for Collection Efficiencies Greater than one Hundred Percent

1997 ◽  
Vol 467 ◽  
Author(s):  
R. Brüggemann ◽  
J. H. Zollondz ◽  
C. Main ◽  
W. Gao
Keyword(s):  
Numerical Modelling ◽  
Absorption Coefficient ◽  
Collection Efficiency ◽  
Photon Flux ◽  
Large Collection ◽  
Probe Light ◽  
Pin Diodes ◽  
Sensor Applications ◽  
Probe Absorption ◽  
Side Bias

ABSTRACTAn account is given for the conditions under which the collection efficiency in hydrogen ated amorphous silicon pin-diodes increases to values larger than 100 %. By specific bias illumination through the p-side bias generated photocarriers are collected under certain probe beam conditions of the collection efficiency measurement, leading to apparent large collection efficiencies. By numerical modelling we investigated the influence of the diode thickness, bias photon flux and probe absorption coefficient as well as applied voltage for possible sensor applications which may utilise this optical amplifying principle. The alternative with bias light through the n-side and probe light through the p-side is also explored. Collection efficiency values determined by the photogating of bias generated holes become only slightly larger than 100 % in contrast to the electron case where values in excess of 3000 % are presented.

The Study of Space Charge Effects by Spectral Response, Steady State Charge Collection and Transient Photocurrents in Thick a-Si:H Pin-Diodes

1996 ◽  
Vol 420 ◽  
Author(s):  
J.-H. Zollondz ◽  
R. Brüggemann ◽  
S. Reynolds ◽  
C. Main ◽  
W. Gao ◽  
...  
Keyword(s):  
Steady State ◽  
Defect Density ◽  
Collection Efficiency ◽  
Spectral Response ◽  
Photon Flux ◽  
Charge Collection ◽  
Internal Variables ◽  
Pin Diodes ◽  
Charge Effects ◽  
Amplification Ratio

AbstractCharge collection, transient photocurrents and collection efficiency under additional bias illumination were used to characterize 3–4 micron thick a-Si:H pin-diodes. The wavelength dependent decrease or increase in the spectral response, depending on the bias flux and absorption depth, is related to the distribution of the electric field, recombination and majority carrier diffusion. At higher photon flux an overshoot in the transient photocurrent after switch-on of steady illumination indicates the time scale for the changes in internal variables. Collection efficiencies under large bias monochromatic photon flux well in excess of the maximum value of 100 % for probe beam generated carriers are observed with a large amplification ratio. These efficiencies sensitively depend both on the applied voltage and the defect density. Numerical modelling reveals the influence of internal variables on the transient and steady state photocurrents under the different illumination conditions.

scholarly journals Determination of X-ray flux using silicon pin diodes

2009 ◽  
Vol 16 (2) ◽  
pp. 143-151 ◽  
Author(s):  
Robin L. Owen ◽  
James M. Holton ◽  
Clemens Schulze-Briese ◽  
Elspeth F. Garman
Keyword(s):  
Light Source ◽  
Energy Deposition ◽  
Photon Flux ◽  
Macromolecular Crystallography ◽  
Pin Diodes ◽  
Web Based ◽  
X Ray ◽  
Swiss Light Source ◽  
Flux Incident

Accurate measurement of photon flux from an X-ray source, a parameter required to calculate the dose absorbed by the sample, is not yet routinely available at macromolecular crystallography beamlines. The development of a model for determining the photon flux incident on pin diodes is described here, and has been tested on the macromolecular crystallography beamlines at both the Swiss Light Source, Villigen, Switzerland, and the Advanced Light Source, Berkeley, USA, at energies between 4 and 18 keV. These experiments have shown that a simple model based on energy deposition in silicon is sufficient for determining the flux incident on high-quality silicon pin diodes. The derivation and validation of this model is presented, and a web-based tool for the use of the macromolecular crystallography and wider synchrotron community is introduced.

Gallium Nitride for Nuclear Batteries

2011 ◽  
Vol 343-344 ◽  
pp. 56-61 ◽  
Author(s):  
Min Lu ◽  
Guo Wang ◽  
Chang Sheng Yao
Keyword(s):  
Gallium Nitride ◽  
Collection Efficiency ◽  
Short Circuit ◽  
Chemical Vapor ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Dead Layer ◽  
Pin Diodes ◽  
Charge Collection Efficiency ◽  
Nuclear Batteries

Gallium Nitride (GaN) PIN betavoltaic nuclear batteries (GB) are demonstrated in our work for the first time. GaN films are grown on sapphire substrates by metalorganic chemical vapor deposition (MOCVD), and then GaN PIN diodes are fabricated by normal micro-fabrication process. Nickel with mass number of 63 (63Ni), which emits β particles, is loaded on the GaN PIN diodes to achieve GB. Current-Voltage (I-V) characteristics shows that the GaN PIN diodes have leakage current of 18 pA at -10V due to consummate fabrication processes, and the open circuit voltage of the GB is estimated about 0.14 V and the short circuit current density is 89.2nAcm-2 . The relative limited performance of the GB is due to thick dead layer and strong backscattering of β particles, Which lead to less energy deposition in GB. However, the conversion efficiency of 1.6% and charge collection efficiency (CCE) of 100% for the GB have been obtained. Therefore, the output power of the GB are expected to greatly increase with thin dead layer and structural surface weakening the backscattering.

Measuring partial fluorescence yield using filtered detectors

2014 ◽  
Vol 21 (4) ◽  
pp. 716-721 ◽  
Author(s):  
T. D. Boyko ◽  
R. J. Green ◽  
A. Moewes ◽  
T. Z. Regier
Keyword(s):  
Dead Time ◽  
Collection Efficiency ◽  
Fluorescence Yield ◽  
Photon Flux ◽  
Linear Attenuation Coefficient ◽  
Edge Structure ◽  
X Ray ◽  
Energy Discrimination ◽  
Energy Dependent ◽  
X Ray Absorption

Typically, X-ray absorption near-edge structure measurements aim to probe the linear attenuation coefficient. These measurements are often carried out using partial fluorescence yield techniques that rely on detectors having photon energy discrimination improving the sensitivity and the signal-to-background ratio of the measured spectra. However, measuring the partial fluorescence yield in the soft X-ray regime with reasonable efficiency requires solid-state detectors, which have limitations due to the inherent dead-time while measuring. Alternatively, many of the available detectors that are not energy dispersive do not suffer from photon count rate limitations. A filter placed in front of one of these detectors will make the energy-dependent efficiency non-linear, thereby changing the responsivity of the detector. It is shown that using an array of filtered X-ray detectors is a viable method for measuring soft X-ray partial fluorescence yield spectra without dead-time. The feasibility of this technique is further demonstrated using α-Fe2O3as an example and it is shown that this detector technology could vastly improve the photon collection efficiency at synchrotrons and that these detectors will allow experiments to be completed with a much lower photon flux reducing X-ray-induced damage.

Numerical Modelling of PIN Diodes

1984 ◽  
Vol 4 (1) ◽  
pp. 43-53 ◽  
Author(s):  
J. M. AITCHISON
Keyword(s):  
Numerical Modelling ◽  
Pin Diodes

Collection Efficiencies Greater Than Unity by Electron Or Hole Gating in a-Si:H p-i-n Diodes

1999 ◽  
Vol 557 ◽  
Author(s):  
J.-H. Zollondz ◽  
C. Main ◽  
S. Reynolds
Keyword(s):  
Probe Beam ◽  
Reverse Bias ◽  
Collection Efficiency ◽  
Simulated Data ◽  
Measured Data ◽  
Lower Mobility ◽  
Electron Gating ◽  
Very High ◽  
Side Bias

AbstractWe report measured electron and hole gating in thick a-Si:H (3.5 μm) p-i-n diodes under reverse bias conditions. Previous publications have shown very high collection efficiency values for electron gating (p-side bias, n-side probe) of up to 50 (i.e. 5000%) for measured and simulated data and predictions of up to 400 (i.e. 40000%) from simulations. Reversing the usual sides of illumination for (electron) gating a situation can be created where, by n-side bias and p-side probe illumination, holes can be gated to travel through the sample to be collected at the contact. Even though the holes have much lower mobility, by this process we can still obtain collection efficiencies greater than unity. This measurement is more difficult because of unwanted illumination by stray bias beam photons on the more sensitive p-side, caused by reflections within the apparatus. Simulation of this situation corroborates qualitatively the measured data. A wide ranging study of the gating phenomenon in relation to different incident wavelengths and photon fluxes for bias and probe beam is reported. We present comparisons of electron and hole gating by measurement and simulation and explain the phenomenon for both electron and hole gating in terms of field changes near to the incident bias interface.

To What Extent are Inelastically Scattered Electrons Useful in the Stem?

1973 ◽  
Vol 31 ◽  
pp. 286-287 ◽  
Author(s):  
H. Rose
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Electron Correlation ◽  
Quantum Noise ◽  
Collection Efficiency ◽  
Scanning Transmission Electron Microscope ◽  
Electron Cloud ◽  
Scanning Time ◽  
Transmission Electron ◽  
Scanning Transmission

The scanning transmission electron microscope offers the possibility of utilizing inelastically scattered electrons. Use of these electrons in addition to the elastically scattered electrons should reduce the scanning time (dose) Which is necessary to keep the quantum noise below a certain level. Hence it should lower the radiation damage. For high resolution, Where the collection efficiency of elastically scattered electrons is small, the use of Inelastically scattered electrons should become more and more favorable because they can all be detected by means of a spectrometer. Unfortunately, the Inelastic scattering Is a non-localized interaction due to the electron-electron correlation, occurring predominantly at the circumference of the atomic electron cloud.

High energy resolution spectrometer for the dedicated STEM

1984 ◽  
Vol 42 ◽  
pp. 558-559 ◽  
Author(s):  
P.E. Batson
Keyword(s):  
Collection Efficiency ◽  
Core Loss ◽  
Beam Current ◽  
High Energy ◽  
High Energy Resolution ◽  
Acquisition Time ◽  
Good Definition ◽  
Loss Analysis ◽  
Definition Of ◽  
Acceleration Voltage

Use of the STEM to obtain precise electronic information has been hampered by the lack of energy loss analysis capable of a resolution and accuracy comparable to the 0.3eV energy width of the Field Emission Source. Recent work by Park, et. al. and earlier by Crewe, et. al. have promised magnetic sector devices that are capable of about 0.75eV resolution at collection angles (about 15mR) which are great enough to allow efficient use of the STEM probe current. These devices are also capable of 0.3eV resolution at smaller collection angles (4-5mR). The problem that arises, however, lies in the fact that, even with the collection efficiency approaching 1.0, several minutes of collection time are necessary for a good definition of a typical core loss or electronic transition. This is a result of the relatively small total beam current (1-10nA) that is available in the dedicated STEM. During this acquisition time, the STEM acceleration voltage may fluctuate by as much as 0.5-1.0V.

High spatial resolution x-ray microanalysis of interfaces

1995 ◽  
Vol 53 ◽  
pp. 284-285
Author(s):  
J. R. Michael
Keyword(s):  
Spatial Resolution ◽  
Electron Probe ◽  
Solid Angle ◽  
Collection Efficiency ◽  
Spatial Scales ◽  
Energy Dispersive Spectrometer ◽  
X Rays ◽  
X Ray ◽  
Probe Size ◽  
Brightness Field

X-ray microanalysis in the analytical electron microscope (AEM) refers to a technique by which chemical composition can be determined on spatial scales of less than 10 nm. There are many factors that influence the quality of x-ray microanalysis. The minimum probe size with sufficient current for microanalysis that can be generated determines the ultimate spatial resolution of each individual microanalysis. However, it is also necessary to collect efficiently the x-rays generated. Modern high brightness field emission gun equipped AEMs can now generate probes that are less than 1 nm in diameter with high probe currents. Improving the x-ray collection solid angle of the solid state energy dispersive spectrometer (EDS) results in more efficient collection of x-ray generated by the interaction of the electron probe with the specimen, thus reducing the minimum detectability limit. The combination of decreased interaction volume due to smaller electron probe size and the increased collection efficiency due to larger solid angle of x-ray collection should enhance our ability to study interfacial segregation.

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