Improved optical properties and detectivity of an uncooled silicon carbide mid-wave infrared optical detector with increased dopant concentration

    Authors

    G. Lim; T. Manzur;A. Kar

    Comments

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    Abbreviated Journal Title

    J. Opt.

    Keywords

    infrared detector; silicon carbide; laser doping; Optics

    Abstract

    An n-type 4H-SiC substrate is doped with gallium using a laser doping technique and its optical response is investigated at the mid-wave infrared (MWIR) wavelength 4.21 mu m as a function of the dopant concentration. The dopant creates a p-type energy level of 0.3 eV, which is the energy of a photon corresponding to the MWIR wavelength 4.21 mu m. Therefore, Ga-doped SiC can be used as an uncooled MWIR detector because an optical signal was obtained at this wavelength when the sample was at room temperature. The energy level of the Ga dopant in the substrate was confirmed by optical absorption spectroscopy. Secondary ion mass spectroscopy ( SIMS) of the doped samples revealed an enhancement in the solid solubility of Ga in the substrate when doping is carried out by increasing the number of laser scans. A higher dopant concentration increases the number of holes in the dopant energy level, enabling photoexcitation of more electrons from the valence band by the incident MWIR photons. The detector performance improves as the dopant concentration increases from 1.15 x 10(19) to 6.25 x 10(20) cm(-3). The detectivity of the optical photodetector is found to be 1.07 x 10(10) cm Hz(1/2) W-1 for the case of doping with four laser passes.

    Journal Title

    Journal of Optics

    Volume

    14

    Issue/Number

    10

    Publication Date

    1-1-2012

    Document Type

    Article

    Language

    English

    First Page

    13

    WOS Identifier

    WOS:000309812400013

    ISSN

    2040-8978

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