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Kurzfassung

The proposed invention concerns ultrafast photoconductors which consists of layers of differently doped adjacent photosensitive semiconductors. These different dopants allow for independent optimization regarding the electron-hole recombination time and the resistance (dark current).

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Hintergrund

Within photoconductors of previous design photosensitive semiconductors can only be optimized towards either electron-hole recombination time or electric resistance. Since the optimum of the one is never the optimum of the other, previous state of the art photoconductors are decidedly less efficient then the proposed ultrafast Multiple-Transition-Metal-doped Short-Period Superlattice Photoconductor.

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Bilder & Videos

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Lösung

A photoconductor as proposed consists of pairs of differently doped very thin (<10nm) layers of semiconductors. Both layers are doped with arbitrary transition-metals (TM) (like Fe, Rh, Ru, or others). Essential is that layer 1 and layer 2 have at least an order of magnitude different doping concentration. The goal is to reach a homogeneous dopant distribution in one layer, and a profound TM-cluster (or other defects) formation in the other layer. Thus the functionality of electrical compensation and the functionality of fast carrier recombination can be split over two layers with different doping levels meaning both functionalities can be optimized simultaneously. These pairs of layers can be optionally mended with spacer layers to prevent interdiffusion of the dopands and this structure is repeated until the total thickness of all layers is between 0,5µm and 2µm.

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Anwendungsbereiche

These photoconductors can be used for terahertz (THz) antennas which are important for transmitting and receiving THz electromagnetic waves in emerging THz systems, e.g. security systems for detecting hazardous material or quality management systems for detecting material defects. Due to small sizes THz antennas usually suffer from a high loss in performance. Since THz waves don’t alter the chemical structure – thus making them safe for use on living beings in contrast to UV and x-ray radiation – THz systems are considered a key future technology. 

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