Optical wavelength response of Ta/p-Si position-sensitive detectors

Jasmine Henry, John Livingstone

    Research output: Contribution to journalArticlepeer-review


    Position-sensitive detectors, PSDs, are precision optical sensors that operate using the lateral photovoltaic effect. Most commercial and, to a large extent, research devices are based on p-i-n structures involving high-temperature diffused junctions. Our programme is aimed at producing devices that perform as well as commercial devices with desirable response characteristics and extended longevity but based on a more straightforward fabrication technique. In this work we investigate the response of one-dimensional Schottky barrier PSDs fabricated using tantalum films deposited on silicon by electron-beam evaporation, a technique which produces very pure and uniform films and permits repeatable devices to be fabricated. Tantalum was selected for its appropriate electronic properties and the potential for forming long-lived, robust and stable detectors. Here we compare the response of these devices at various thicknesses under different light sources. An optimal thickness of tantalum, trading off transmissivity against good Schottky barrier formation, has been determined as approximately 200Angstrom. These devices were tested under various light sources: white light, filtered light and a red diode laser. The best properties were found under a 5 mW red broadband filtered light, producing better than 7 mV/mm and excellent linearity.
    Original languageEnglish
    Pages (from-to)613 - 625
    JournalInternational Journal of Electronics
    Issue number10
    Publication statusPublished - 2003


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