Spektralselektive optoelektronische Sensoren auf der Basis amorphen Siliziums

This Ph.D. thesis deals with spectrally selective optoelectronic sensors based on amorphous silicon. The most important feature of this novel detector type is its voltage controlled spectral sensitivity, originating from the wavelength dependence of optical absorption inside the thin film multilayer structures in conjunction with a corresponding drift profile for charge carriers. In this way a single device is able to generate a complete RGB color signal.
The thesis documents various steps of development in which different types of bipolar and unipolar color detectors have been realized and optimized. The endpoint of the development is represented by the trichromatic unipolar sensor of pi 3 n type which combines good color separation and a high dynamic range. Moreover, this detector exhibits reasonable read out speed. The color reproduction performance of the device can be regarded as comparable to
conventional color sensors using optical filters.
The development of the color detectors gains special importance in the framework of TFA technology (Thin Film on ASIC), a novel technology for realization of image sensors, combining the excellent electrooptical properties of photodetectors based on amorphous silicon with powerful and flexible ASIC technology. Immediately before completion of this thesis a TFA color sensor array has been demonstrated successfully for the first time. The TFA imager makes use of an unipolar three color sensor that has been developed by the author. This fact already shows that the innovative color sensor technology guides the way to a new generation of color imagers to be employed in many fields of applications ranging from digital photography to complex industrial color image processing systems.