Comparison of Exact and Measured Open Circuit Photoconductor Voltages
Robert J. Mattauch · Review of Scientific Instruments · 1969
It is necessary to determine the open circuit voltage of a photoconductor in order to find its responsivity and detectivity. The ideal case of a photodetector in series with an ideal current source is analyzed and an expression for the open circuit device voltage is given. Since this case is almost impossible to obtain in the laboratory with devices of 10x Ω internal impedance where x>7 and a bias of several hundred volts across the device is needed, the realistic nonideal current source case is treated. It is shown that what is believed to be the actual open circuit device voltage can be incorrect by as much as 10% in certain cases. The conditions necessary for accuracy are given along with curves enabling one to determine accurately the device open circuit voltage if these conditions are not met.