Noise in Semiconductor IR Detectors

In this section, we give a brief phenomenological description of noise in photonic detectors. Only the most basic practical details are included necessary for us to consider the possibilities to decrease it. An attempt has been made to give a theory valid simultaneously for photoconductors and photovoltaics. 

We define intrinsic noise of an electron device as stochastic fluctuations of its electrical signal caused by internal processes in the device. The noise value in any moment will not be in correlation with its value in any other moment. A momentary value of noise cannot be measured, but only a sample in a given time interval determined by A/. No electron device is completely noise-firee. There are two fundamental reasons for noise appearance in photon detectors with an electric current flow fluctuations of the number of carriers and fluctuations of the carrier velocity. 

The main (but not the only) reason for the appearance of carrier number fluctuations are generation-recombination processes, i.e., the same processes that enable the very operation of the device and define both the dark current of the device and its optically generated signal. 

Fluctuations of carrier velocity are a result of the Brownian nature of carrier motion within semiconductor material. They are a consequence of the fact that semiconductor material is at a temperature different than zero. 

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