Properties of Germanium Doped with Iron. II. Photoconductivity

Photoconductivity in n- and p-type Fe-doped Ge was measured at 77^. The impurity photoconduction in both types has approximately the same spectral dependence, indicating ionization energies of about 0. 3 ev. The intrinsic photoconductive response measured at 0. 83 ev was found to be a function of sample composition, the photosensitivity increasing as the samples became more n-type. Intrinsic photosensitivity and the time of response seem linearly related. For n-type samples of highest sensitivity the minimum detectable radiation level at 0. 83 ev was estimated to be 210^-13 watt. In such samples quenching effects were found in the spectral region from 0. 3 ev to 0. 7 ev. Experimental results are discussed in terms of a model in which the impurity center is capable of accepting two excess electrons.