Temperature dependence of photoconductivity for amorphous HgCdTe films

To provide a better material than MCT for photoelectronic devices, amorphous Hg1-xCdxTe (a-MCT) as a new material is studied. Cr/Au alloy was deposited as both upper and bottom electrodes. a-MCT (x=0.2) films were grown on bottom electrodes, being sandwich device structure. The relation between photoconductivity and temperature was studied for the prototype devices under dark background and illuminated condition, respectively. The SR20 blackbody is used as infrared radiation source. The photoconductivity is obtained by DC and AC measurements within temperature range from 77K to 300K. There are different photoconductivity characteristic in three independent temperature ranges, namely high temperature regimeI(240-300K), middle temperature regimeII (140-240K), and low temperature regimeIII (77-140K). It was shown that, T=240K is the turning point from σph-T curves and is also maximal optical response temperature. In different regimes, the behavior of photoconductivity is due to carriers mobility and non-equilibrium carriers density. © 2009 SPIE.