Amorphous Silicon Three Color Detector

1995 ◽  
Vol 377 ◽  
Author(s):  
H. Stiebig ◽  
J. Giehl ◽  
D. Knipp ◽  
P. Rieve ◽  
M. Böhm
Keyword(s):  
Amorphous Silicon ◽  
Analytical Model ◽  
Integrated Circuit ◽  
Dynamic Range ◽  
Circuit Simulation ◽  
Spectral Response ◽  
Simulation Program ◽  
Response Curves ◽  
Pool Model ◽  
Color Sensors

ABSTRACTBand gap and defect engineered amorphous silicon based nipin photo diodes with bias controlled spectral response have been fabricated successfully. The devices exhibit good linearity over a wide illumination range and linearly independent spectral response curves which are required to generate a standard RGB-signal. In the bias range from -1.5 V to 1.5 V a dynamic range exceeding 90 dB for two color sensors and 80 dB for three color sensors has been observed. The general operation principle of the multispectral photo diode is discussed using a numerical simulation program. The model describes the defect state distribution of dangling bonds according to the defect-pool model and uses coherent wave propagation in the device to calculate the profile of photo generated carriers. Additionally, an analytical model has been developed to be included into standard circuit simulation programs like SPICE (Simulation Program with Integrated Circuit Emphasis). The analytical model uses linear field approximations in both i-layers of the device.

Fast Color Detection with Two-Terminal P-I-I-N Devices

1996 ◽  
Vol 420 ◽  
Author(s):  
T. Neidlinger ◽  
M. B. Schubert ◽  
G. Schmid ◽  
H. Brummack
Keyword(s):  
Dynamic Range ◽  
Spectral Response ◽  
Hole Transport ◽  
Color Sensor ◽  
Color Separation ◽  
Color Detection ◽  
Color Sensors ◽  
Voltage Transients ◽  
Different Color ◽  
Electric Field Profile

AbstractIn order to overcome the intrinsic speed limitation of amorphous silicon nipin color sensors we present an alternative way of achieving bias-controlled spectral sensitivity of two-terminal thin film devices, piin structures with appropriate band gap and thickness of their single layers can be used as photodetectors that are able to sequentially extract different color signals. Color separation is achieved by controlling the absorption and electric field profile across these piin devices, and thanks to the differences in electron and hole transport properties. Because in contrast to nipin devices there is no need for reverting readout voltages for color separation, this type of sensors can be operated at much higher readout frequencies. Spectral response and bias voltage transients have been analysed up to 20kHz, and preliminiary data are presented on the optimization of speed, dynamic range and color separation by varying bandgap and thickness of p- and i-layers. Furthermore a three-color sensor has been realized by introducing an additional intrinsic layer.

Two-Dimensional Amorphous Silicon Color Sensor Array

2001 ◽  
Vol 664 ◽  
Author(s):  
F. Lemmi ◽  
M. Mulato ◽  
J. Ho ◽  
R. Lau ◽  
J. P. Lu ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Dynamic Range ◽  
Imaging System ◽  
Color Image ◽  
Two Dimensional ◽  
Leakage Currents ◽  
Color Sensor ◽  
Low Leakage ◽  
Color Sensors ◽  
Silicon Based

ABSTRACTThis paper reports on the first full realization and characterization of a two-dimensional array of amorphous silicon (a-Si:H) color sensors, addressed by integrated amorphous silicon-based thin-film transistors (TFTs). The array includes 512 × 512 pixels with 75-µm pitch, or about 340 dpi. Each pixel features a color sensor realized by a p-i-n-i-p stack of doped and undoped a-Si:H layers, and the TFT. The color sensors are made of two back-to-back p-i-n diodes, which selectively sense the illumination according to the polarity of the applied bias voltage. The sensor layers are grown on top of the TFTs to improve the array fill factor. The p-in-i-p sensor stack is mesa-isolated into single sensors to reduce cross-talk.Images are acquired using two bias voltages and yield the red and blue/green components of the original with a good color separation. A color image is reconstructed using the information from the two images acquired. Aside from a color bias, which is expected for a two-color reconstruction, the imaging system works well. In particular, the array shows very low leakage currents, which enable a very large dynamic range and sensitivity. In the response of the array to a light pulse, the bottom thick diode ensures a fast drop in the signal after the flash, while the top thin diode exhibits some residual image lag.

Improved Concept for Nipiin and PIIIN Color Sensitive Two-Terminal Devices with High Linearity

1997 ◽  
Vol 467 ◽  
Author(s):  
D. Knipp ◽  
H. Stiebig ◽  
J. Fölsch ◽  
R. Carius ◽  
H. Wagner
Keyword(s):  
Light Intensity ◽  
Dynamic Range ◽  
Layer Structure ◽  
Spectral Response ◽  
Incident Light ◽  
High Dynamic Range ◽  
Optical Signal ◽  
Optimized Design ◽  
Defect States ◽  
Response Curves

ABSTRACTThe detection of the fundamental components of the visible light (blue, green, red) is achieved with two terminal photo diodes based on amorphous silicon. By changing the bias voltage the preferential carrier collection region is shifted which leads to a color sensitivity. In order to obtain a high dynamic range, independent voltage controlled spectral response curves as well as a linear response of the photocurrent on the incident light intensity the μτ-product and the bandgap in the device have to be specially designed to deconvolute the optical signal and generate an RGB-signal. Since the light intensity can strongly influence the spectral sensitivity by recharging of defect states, an optimized design of the multi-layer structure is necessary. Therefore, an improved concept for the design of nipiin- and piiin-detectors is presented which results in a good suppression of these non-linearities. Our concept is based on a decreasing bandgap profile from the front to the back contact and an increasing μτ-product of the individual i-layers in direction of the p-layer.

scholarly journals Using Spice Circuit Simulation Program in Reliability Analysis of Redundant Systems with Non-Repairable Units and Common-Cause Failures

2000 ◽  
Vol 22 (4) ◽  
pp. 235-255 ◽  
Author(s):  
Muhammad Taher Abuelma'atti ◽  
Isa Salman Qamber
Keyword(s):  
Integrated Circuit ◽  
Markov Models ◽  
Circuit Simulation ◽  
Simulation Program ◽  
Time To Failure ◽  
Transform Method ◽  
Common Cause ◽  
The Laplace Transform ◽  
Common Cause Failures ◽  
Redundant Systems

The effectiveness of Simulation Program with Integrated Circuit Emphasis (SPICE) in calculating probabilities, reliability, steady-state availability and mean-time to failure of redundant systems with non-repairable units and common-cause failures described by Markov models is demonstrated. General equations and procedure for constructing the equivalent circuit forNparallel units are presented. Results obtained, forN=1,2,3, using SPICE are compared with previously published results obtained using the Laplace transform method. Full SPICE listings are included.

Spectral Response of a-Si:H p-i-n Solar Cells Degraded by Blue and Red Light

1995 ◽  
Vol 377 ◽  
Author(s):  
A. Mittiga ◽  
L. Mariuc ◽  
T. Fasolino ◽  
A. Romano ◽  
P. Fiorini ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Spatial Distribution ◽  
Solar Cells ◽  
Blue Light ◽  
Spectral Response ◽  
Red Light ◽  
Experimental Results ◽  
Simulation Program ◽  
Total Density ◽  
Response Curves

ABSTRACTWe have degraded a-Si:H p-i-n solar cells at Voc using both red and blue light to investigate the effect of a possible different spatial distribution of defects in the intrinsic layer. We have found that the I-V and the spectral response curves of the degraded cells depend on the total density of defects only and are not sensitive to the wavelength of the degradation light. These experimental results and some peculiar features of the spectral response of the degraded cells are explained with the aid of a numerical simulation program.

A New Device Model of Amorphous Silicon Thin-Film Transistor for Circuit Simulation

1991 ◽  
Vol 219 ◽  
Author(s):  
Hong S. Choi ◽  
Jin S. Park ◽  
Chang H. Oh ◽  
In S. Joo ◽  
Yong S. Kim ◽  
...  
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Analytical Model ◽  
Circuit Simulation ◽  
Thin Film Transistor ◽  
Drain Current ◽  
Channel Length ◽  
Silicon Thin Film ◽  
New Device ◽  
Circuit Simulator

ABSTRACTWe present a new analytical model of amorphous silicon thin-film transistor (a-Si TFT) suitable for circuit simulators such as SPICE. The effects of localized gap state distributions of a-Si as well as temperatures on the a-Si TFT performances have been fully considered in the presented model. The parameters used in SPICE, such as transconductance, channel-length modulation, and power factor of source-drain current, are evaluated from the measured current-voltage and capacitance-voltage characteristics by employing the proposed extraction method. It has been found out that the analytical model is in good agreement with experimental data at both room temperature and elevated temperature and successfully implemented in a widely used circuit simulator.

scholarly journals PHOTOMETRIC CHARACTERIZATION OF A COMMERCIAL DSLR CAMERA FOR THE IMPLEMENTATION OF AN IMAGING LUMINANCE METER

Anales AFA ◽  
2021 ◽  
Vol 31 (4) ◽  
pp. 143-149
Author(s):  
O. U. Preciado ◽  
◽  
A. Décima ◽  
J.B. Barraza ◽  
◽  
...  
Keyword(s):  
Dynamic Range ◽  
Spectral Response ◽  
High Dynamic Range ◽  
Absolute Calibration ◽  
Successful Implementation ◽  
Pilot Test ◽  
Response Curves ◽  
Cmos Sensor ◽  
High Dynamic

In this paper we describe the procedure followed in the photometric characterization of a DSLR camera in order to implement an imaging luminance meter. The first step consisted in the experimental setup of a system to obtain the spectral response curves of the CMOS sensor for its three channels: red (R), green (G) and blue (B). Then, based on the linear combination of the RGB channel curves, we calculated an approximation of the CIE luminous efficiency function, V(λ), for the camera. We then characterized the camera lens which involved measuring its spectral transmittance and evaluating the uniformity of the lens-sensor assembly to compensate for loss of sensitivity at the image periphery (vignetting). Finally, we performed an absolute calibration in luminance and carried out a pilot test to create high dynamic range (HDR) images and luminance maps of a scene. The favourable results of the pilot test augur a successful implementation of the image luminance meter, however, it is necessary to finish with the development of a software for the image processing and to do more tests in order to be able to validate its use in different situations or to establish the restrictions of its use.

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