p-i-n flexible imaging devices with optical readout

Large area two terminal p-i-n image sensors deposited on plastic substrates were produced at low temperatures (110 °C) by PE-CVD and compared with similar sensors deposited on glass substrates. The same sensing element structure ZnO:Al/p(SiC:H)/i(Si:H)/n(SiC:H)/Al was used in all devices although with different resistivities of the front contact. In this work the efforts are focused mainly on the optimization of the output characteristics of the sensor when fabricated on plastic substrates. The role of the sensor configuration, front contact resistivity and readout parameters on the image acquisition process is analyzed. The optical-to-electrical transfer characteristics show reasonable quantum efficiency under a red light pattern, broad spectral response, and reciprocity between light and image signal. First results show that the sensors deposited on flexible substrate present smaller light to dark sensitivity than those deposited on glass. In both, the non ohmic behavior of the transparent conductive oxide front contact blocks the carrier collection and leads to a surprising linear dependence of the image signal on the applied voltage.