Researches On Crosstalk Induced By Light In The Infrared TDI Array Detector Of PV-HgCdTe

In infrared imaging system,crosstalk could reduce intelligibility of image,affect the resolution of focal plane array and decrease imaging quality,so researches on crosstalk mechanism are very important.Crosstalk mechanism of infrared TDI HgCdTe array detector which is considered as a new generation product will be systematically studied in this paper.At first,two kinds of crosstalk mechanism and three test principles and methods of crosstalk have been compared.Optical crosstalks induced by reflection,refraction,scatter,diffraction and aberration are discussed.And then electrical crosstalk induced by characteristic parameters of carriers which include diffusion,concentration,diffusion length and absorption coefficient,radiation recombination,surface channel,photosensitive unit and processed circuit design are discussed.Solutions of optical & electrical crosstalk based on structure design,process improvement and circuit technology optimization of the device are also introduced.On the basis of these analyses above,the crosstalk mechanism of in and out of the peak response band of infrared TDI HgCdTe array detector have been investigated,at the same time,the relationships between optical crosstalk and the wavelength,power or frequency of incident light,and optical crosstalk in irradiated channel and dark channel have been also studied.The main conclusions are as follows.1.Experiments have discovered that when the power of incident light increases a certain degree,either 3800 nm which is in the response band or 1064 nm which is out of the peak response band,the crosstalk effect has been detected both in irradiated channel and dark channel,and the crosstalk effect is going up until all the detection units reach saturation with the increase of power.When the power of 3800 nm is the same as 1064 nm,the degree of crosstalk in the wave band is greater than out of the peak response band.2.When the power of incident light in the wave band is between 3.0 W/cm~2 and 9.8×10~2 W/cm~2,there is an approximate linear relationship between the double logarithmic coordinates of the number of detection units of crosstalk and the power of incident light whether for irradiated channels or for dark channels.And the slope of the curve is 0.36 and 0.46 respectively.The researches show that the optical crosstalk caused by diffraction effect is the main source of the crosstalk of the irradiation channels.The main source of the crosstalk of the non irradiated channel is the electrical crosstalk caused by the movement of carriers induced by light.3.When the power of incident light in the wave band is between 0.8 W/cm~2 and 1.9×10~2 W/cm~2,there is an approximate linear relationship between the double logarithmic coordinates of the number of detection units of crosstalk and the power of incident light whether for irradiated channels or for dark channels.And the slope of the curve is 0.39 and 0.51 respectively.The researches show that the optical crosstalk caused by diffraction effect is the main source of the crosstalk of the irradiation channels.The main source of the crosstalk of the non irradiated channel is the electrical crosstalk caused by the movement of carriers induced by light.4.Experiments have discovered a new symmetric response phenomenon that is different from continuous light when low frequency pulsed light irradiates infrared TDI HgCdTe array detector,which is symmetric distribution in the voltage output curve of detector appears.Researches show that the frequency of pulse laser is smaller so that the incident time of pulsed laser is inconsistent with the integration period,which caused the symmetric distribution of the voltage output curve of detector.