Study On The Mechanism Of Output-decrease Of Array HgCdTe Detector Induced By Laser

Array type HgCdTe photodetector has been widely used in production,life and other fields.In the study of its laser irradiation,a series of abnormal phenomena such as output-decrease induced by high power density of light were found,hindering the scope of use and application of such devices.This article focused on the abnormal phenomenon that occurs in array type HgCdTe photodetector,by simulating the readout circuit of the detector and the irradiation effect of the photosensitive chip,reveals the mechanism of its generation,making important reference value for improving the performance of photodetectors and processing technology.The main research work and conclusions are as follows:1.Studying the distribution and variation of photo-generated carriers concentration in the photosensitive materials of the detector chip with time under laser irradiation.During laser irradiation,it was found that there was a state of disappearance of the PN junction,and the chip’s electrical properties changes from semiconductor into conductor.In addition,under temperature field,the temperature difference electromotive force will be generated inside the chip,which will cancel out part of the built-in electric field of the PN junction and reduce the photovoltaic effect of the PN junction.And the read-out circuit make the chip generate a current flowing to the common P electrode,which may cause damage to the circuit in experiments.2.Studying the circuit effect on the detector output voltage.Researches show that the output voltage of the readout circuit is linearly related to the electric potential difference across the detector,the decrease in voltage across the detector causes the output voltage to drop synchronously,and the increase of the common supply V_b makes the voltage value at the negative input of the amplifier rise,then in turn the value of the output voltage decreases.3.Revealing the mechanism of output-decrease induced by laser.Under high power density of laser irradiation,an excess of photo-generated carriers will be generated inside the detector chip,changing the structure of the PN junction inside the detector chip,weakens the photovoltaic effect of the PN junction,which results in a decrease in the output voltage of the readout circuit.