Photovoltaic effect in the impurity absorption region of Si-structures with blocked impurity conductivity

A study is made of the field dependence of the photoconductivity in two-layer Si:Sb-and Si:Bstructures with blocked impurity-band conductivity and different thicknesses of the undoped (blocking) layer. The impurity concentration in the doped (active) layer was ≈1018 cm−3. Measurements were made at temperatures T=4–15 K for high (Φ∼1016 photons/cm2 · s) and low (Φ 1013 photons/cm2 · s) and, in the limit of low temperatures, it is close to the activation energy ɛ3 for jump conductivity in the active layer. The photovoltaic effect is explained by ballistic transit of the blocking layer by holes emitted from the contact which are then cooled in the active layer, as well as by the presence of a potential barrier ≈ɛ3 between the active and blocking layers. These factors are taken into account in a model for describing the major features of the dependence of the photovoltage on temperature and on the photon intensity and energy.