By Topic

Amorphous silicon phototransistor as nonlinear optical device for high dynamic range imagers

Sign In

Cookies must be enabled to login.After enabling cookies , please use refresh or reload or ctrl+f5 on the browser for the login options.

Formats Non-Member Member
$31 $13
Learn how you can qualify for the best price for this item!
Become an IEEE Member or Subscribe to
IEEE Xplore for exclusive pricing!
close button

puzzle piece

IEEE membership options for an individual and IEEE Xplore subscriptions for an organization offer the most affordable access to essential journal articles, conference papers, standards, eBooks, and eLearning courses.

Learn more about:

IEEE membership

IEEE Xplore subscriptions

2 Author(s)
Nascetti, A. ; Dept. of Electron. Eng., Rome Univ., Italy ; Caputo, D.

An amorphous silicon bulk barrier phototransistor is studied as a basic element for the pixel of high dynamic photosensor arrays. The device is an n-i-δp-i-n structure whose optical gain shows a nonlinear dependence on the illumination intensity. For each applied bias voltage, a quasi-hyperbolic decrease of the optical gain as a function of the incident power is found. This behavior can be explained taking into account both the material characteristics (defect distribution, dopant concentration), and the structure properties. Our measurements lead to a minimum detectable signal of about 0.7 nW/cm2 independently on the applied voltage, making the device suitable for low illumination conditions. On the other hand, by increasing the input power up to 35 mW/cm2, we did not find saturation of output photocurrent leading to a dynamic range of at least of 120 dB. This value can be further increased by using as basic cell of the pixel the phototransistor and a resistor connected between the voltage supply and the collector electrode

Published in:

Electron Devices, IEEE Transactions on  (Volume:49 ,  Issue: 3 )