Interface properties of nanocrystalline-FeSi 2/Crystalline-Si near-infrared heterojunction photodiodes

Mahmoud Shaban, Tsuyoshi Yoshitake

    Research output: Contribution to journalArticlepeer-review

    3 Citations (Scopus)


    In this paper, we experimentally charactize n-type nanocrystalline iron disilicide films (NC- FeSi 2), grown on p-type single-crystalline Si substrates at room temperature by a facing-target direct-current sputtering method. These p-n heterojunction devices are promising candidates for near-infrared photodiode applications. However, their current-voltage characteristics show large leakage currents, which limit the device functions. Hence, we have calculated the energy band diagram of the NC- FeSi2/Si heterojunction, for the first time, to gain insight into the source of this leakage. The conduction and valance band discontinuities are calculated as 0.19 and 0.46 eV, respectively. A built-in potential of 1 V is estimated from the energy band diagram. This estimate is almost twice the value obtained from the measured capacitance-voltage characteristics. This indicates the presence of a large number of defects at the heterojunction interface. From a simulation combined with the experimental results, the defect density is estimated to be at least 1.3 × 10 -2. The simulation model successfully reproduces the experimental current-voltage characteristics of the device and reveals that acceptor-like interface states centered at approximately 0.35 eV above the valance band are the main sources of the heterojunction leakage. Simulation results predict that passivation of these defects would reduce the leakage current to 10 2, causing significant improvements in the device's performance.

    Original languageEnglish
    Article number6310088
    Pages (from-to)1432-1438
    Number of pages7
    JournalIEEE Journal of Quantum Electronics
    Issue number11
    Publication statusPublished - 2012

    All Science Journal Classification (ASJC) codes

    • Atomic and Molecular Physics, and Optics
    • Condensed Matter Physics
    • Electrical and Electronic Engineering


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