Backgroundless absorption spectrum of Pb1-xSnxTe and thickness dependence of epitaxial-layer photoconduction

Direct backgroundless measurements of spectrum and kinetics of the absorption coefficient α(η ν) for Pb1-xSnxTe (x∼=0.23) at 4.2 K are conducted. The contribution of intracentric absorption into α is determined. It is shown that surface states and surface recombination do not produce noticeable effect on photoconductivity. The concentration of deep centres in the material: Nd∼=4x1017 cm-3 is estimated based on obtained data, that is much less than the concentration of indium impurity N(In)=1x1019 cm-3. Cross section of absorption for negative and positive photoeffects , which are respectively equal to s1=4x10-14 and s2=5x10-15 cm2 are estimated