Abstract: The influence of background radiation on a medium-wave HgCdTe photoconductive detector with an overlap structure is studied.In the experiment design,two methods are put forward to change the background radiation.It is found that the detector noise decreases with the decrease of the background radiation.The g-r noise is calculated from the number of carriers and lifetime theory.It is shown that the calculation result has the same trend as the experimentally observed phenomena.Further noise spectrum measurement shows that 1/f noise is the primary factor that causes the detector noise to change with background radiation.The edge contacts’ asymmetrical MIS structure increases the effect of background radiation on the 1/f noise.

Key words: HgCdTe, overlap structure, background radiation, noise