Stacked amorphous silicon color sensors

Color sensors based on vertically integrated thin-film structures of amorphous silicon (a-Si:H) and its alloys were realized to overcome color moire or color aliasing effects. The complete color information of the color aliasing free sensors is detected at the same spatial position without the application of additional optical filters. The color separation is realized in the depth of the structure due to the strong wavelength dependent absorption of a-Si: H alloys in the visible range. The sensors consist of three stacked p-i-n diodes. The spectral sensitivity of the sensors can be controlled by the optical and electronic properties of the materials on one hand and the design of the devices on the other hand. In order to investigate the optical wave propagation within the device and to optimize the color separation we have developed an optical model, which takes the optical properties of the individual layers and the device design into account. The optical model has been combined with a colorimetric model, which facilitates the benchmarking of the color sensors and the reduction of the color error of the sensors. Finally, an improved device design is presented