Voltage-controlled, wavelength-selective photodetector

The invention relates to a voltage-controlled, wavelength-selective photodetector comprising a double diode consisting of a counter-polarized Si-Schottky diode and a SiGe PIN diode. The short-wave portion (μ∫ 0.9 νm) of the light entering the detector through a window preferably generates electron-hole pairs in the Si-Schottky diode, while the longer-wave portion (1 νm ∫μ∫ 2 νm) passes through the substrate and is preferably absorbed in the epitaxially deposited SiGe superlattice or the quantum well diode. The photocurrents of both detectors flow in physically opposite directions and subtract from each other, resulting in a wavelength-dependent operational sign of the photocurrent. The level of the bias voltage applied determines whether the photocurrent of the Si-Schottky diode or the photocurrent of the Si/Ge PIN diode determines the spectrum. This can be used, for example, in an application for decoding signals by transforming the light signal into an electrical output signal and subtracting the photocurrents of the two detectors which filters out exactly the noise component and thus raises the signal/noise ratio of a light signal