Figure of merit of diamond power devices based on accurately estimated impact ionization processes

Atsushi Hiraiwa, Hiroshi Kawarada

    Research output: Contribution to journalArticle

    24 Citations (Scopus)

    Abstract

    Although a high breakdown voltage or field is considered as a major advantage of diamond, there has been a large difference in breakdown voltages or fields of diamond devices in literature. Most of these apparently contradictory results did not correctly reflect material properties because of specific device designs, such as punch-through structure and insufficient edge termination. Once these data were removed, the remaining few results, including a record-high breakdown field of 20 MV/cm, were theoretically reproduced, exactly calculating ionization integrals based on the ionization coefficients that were obtained after compensating for possible errors involved in reported theoretical values. In this compensation, we newly developed a method for extracting an ionization coefficient from an arbitrary relationship between breakdown voltage and doping density in the Chynoweth's framework. The breakdown field of diamond was estimated to depend on the doping density more than other materials, and accordingly required to be compared at the same doping density. The figure of merit (FOM) of diamond devices, obtained using these breakdown data, was comparable to the FOMs of 4H-SiC and Wurtzite-GaN devices at room temperature, but was projected to be larger than the latter by more than one order of magnitude at higher temperatures about 300°C. Considering the relatively undeveloped state of diamond technology, there is room for further enhancement of the diamond FOM, improving breakdown voltage and mobility. Through these investigations, junction breakdown was found to be initiated by electrons or holes in a p--type or n--type drift layer, respectively. The breakdown voltages in the two types of drift layers differed from each other in a strict sense but were practically the same. Hence, we do not need to care about the conduction type of drift layers, but should rather exactly calculate the ionization integral without approximating ionization coefficients by a power function of electric field as often done in Si devices. In order to facilitate this approach, we developed a method for simplifying the ionization integral, which method, together with the aforementioned method for extracting ionization coefficients, will help to promote the study on breakdown phenomena of all semiconductors.

    Original languageEnglish
    Article number034506
    JournalJournal of Applied Physics
    Volume114
    Issue number3
    DOIs
    Publication statusPublished - 2013 Jul 21

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    figure of merit
    ionization coefficients
    electrical faults
    diamonds
    ionization
    breakdown
    punches
    wurtzite
    rooms
    conduction
    electric fields
    augmentation
    room temperature
    electrons

    ASJC Scopus subject areas

    • Physics and Astronomy(all)

    Cite this

    Figure of merit of diamond power devices based on accurately estimated impact ionization processes. / Hiraiwa, Atsushi; Kawarada, Hiroshi.

    In: Journal of Applied Physics, Vol. 114, No. 3, 034506, 21.07.2013.

    Research output: Contribution to journalArticle

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