| 摘要 |
A two-layer, narrow bandwidth photovoltaic detector prepared from single crystal films epitaxially grown to controlled thicknesses from materials of selected compositions upon opposite parallel faces of a transparent substrate. Alternately, the two layers may be grown layer-to-layer, perhaps with either of the layers adjoining one face of a substrate. In either configuration, one of the layers serves as a filter of incident radiation while the other layer acts as a detector of radiation passing through the filter layer. Where the layers are separated by a transparent substrate, the composition of the filter layer is chosen so that its energy gap equals or exceeds the energy gap exhibited by the composition chosen for the detector layer. If the layers are grown layer-on-layer, the energy gap of the filter layer should exceed the energy gap of the detector layer. Detector layer may be used as a photoconductor or, with the creation of a heterojunction, as a photovoltaic detector. The thickness of either or both layers may be chosen to make the layers anti-reflective at the peak wavelength responsivity (or wavelengths) of the device. |
