Nonlinear far-infrared photoconductivity in Ge:Ga

Publisher Website
Google Scholar
Abstract
We report the observation of photoconductivity in Ge:Ga (NA =3× 1016 cm−3 and 8×1015 cm−3) at 4.2 °K, using high‐intensity, far‐infrared radiation (I≂10 kW/cm2; λ=496 μm). This observation is unexpected since the impurity ionization potential (Ei =10.97 meV) is greater than the photon energy (hν=2.5 meV). The excitation of holes into the valence band is confirmed by the large decrease in sample resistance (from ∼MΩ to ≤20 Ω) and the decrease in transmission at high intensities. A two‐step excitation model matches the behavior of the intensity dependence of the photoconductivity.