The experimental results reviewed in this paper cover the following topics: optical absorption and steady-state photoconductivity of amorphous single layer structures Al-As0.40S0.30Se0.30-Al, Al-Ge0.09As0.09Se0.82-Al, Al-Ge0.30As0.04S0.66-Al and heterostructures (HS) Al-As0.40S0.30Se0.30 / Ge0.09As0.09Se0.82 / Ge0.30As0.04S0.66-Al as well. The thickness of each layer of the HS is around 1, 0.5 and 0.2 μm, respectively. It was found that the voltage dependence on the photocurrent can be varied with both the polarity of the top illuminated electrode and different excitation wavelengths. Some photocurrent spectra show rich structure which originate due to different value of the optical band gap of the amorphous interlayers (about 2.0 eV for the As0.40S0.30Se0.30 and Ge0.09As0.09Se0.82, and about 3.0 eV for the Ge0.30As0.04S0.66). The obtained experimental results are discussed taking into account the absorption depth of the incident light, the contact phenomena between the layer interfaces of the different compositions as well as the interfaces metal-amorphous semiconductor layer.