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Author: search.filters.author.Promros, NathapornSubject: search.filters.subject.FTDCS

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    Production of p-Type Si/n-Type β-FeSi2 Heterojunctions Using Facing-Targets Direct-Current Sputtering and Evaluation of Their Resistance and Interface State Density
    (2018-10-24)
    Chaleawpong, Rawiwan
    ;
    Promros, Nathaporn
    ;
    Charoenyuenyao, Peerasil
    ;
    Nopparuchikun, Adison
    ;
    Sittimart, Phongsaphak
    Without a post-annealing procedure, the β-FeSi<inf>2</inf> thin films are epitaxially grown on Si(111) wafer substrates via facing-targets direct-current sputtering. During epitaxial growth, the temperature for heating of substrates is maintained at 600 °C. The resultant p-type Si/n-type β-FeSi<inf>2</inf> heterojunctions are produced. At room temperature, a large leakage current under an applied reverse bias voltage together with a small photo-detective performance is observed from the measured dark and irradiated current density–voltage curves of the created heterojunctions. Both of the conductance–voltage (G/ω–V) and capacitance–voltage (C–V) measurements at different frequencies (f) in the range of 5 kHz–1 MHz are performed in the dark at room temperature. The interface state density (N<inf>ss</inf>) and series resistance (R<inf>s</inf>) in the created p-type Si/n-type β-FeSi<inf>2</inf> heterojunctions are computed and analyzed from the measured C–V–f and G/ω–V–f curves. N<inf>ss</inf> is found to be 3.48 × 10<sup>12</sup> eV<sup>−1</sup> cm<sup>−2</sup> at 5 kHz and decreased to 4.68 × 10<sup>11</sup> eV<sup>−1</sup> cm<sup>−2</sup> at 1 MHz. Moreover, the values of R<inf>s</inf> at zero bias are 2.21 kΩ at 5 kHz and 13.66 Ω at 1 MHz. These results review the presence of N<inf>ss</inf> and R<inf>s</inf> in the created heterojunctions, and they can be the cause to degrade the heterojunction performance.
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    Investigation of electrical transport properties in heterojunctions comprised of silicon substrate and nanocrystalline iron disilicide films
    (2016-01-01)
    Promros, Nathaporn
    ;
    Sittimart, Phongsaphak
    ;
    Kaenrai, Weerasaruth
    In this study, n-type nanocrystalline FeSi<inf>2</inf>/p-type Si heterojunctions were fabricated using facing-target direct-current sputtering (FTDCS). The possible transportation mechanisms of carriers were investigated by analysing the dark J-V characteristics at temperatures ranging between 60 and 300 K. The ideality factor (n) was estimated from the slope of the linear region for the forward lnJ-V characteristics. The value of n was 1.87 at 300 K and nearly constant at temperatures ranging from 140 to 300 K, suggesting that a recombination process at the junction interface was dominant in the transportation mechanism of carriers. At temperatures below 140 K, the value of n increased by more than two and the value of A was virtually constant. Owing to the consistency of A, combined with the temperature dependent value of n, the implication is that a trap-assisted multi-step tunnelling mechanism governed the carrier transport. From the analysis of J-V characteristics, the value of barrier height was 0.58 eV at 300 K and decreased to 0.19 eV at 60 K.
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    Current transport mechanism of n-type nanocrystalline FeSi2/intrinsic si/p-type si heterojunctions fabricated by facing-targets direct-current sputtering
    (2013-10-29)
    Promros, Nathaporn
    ;
    Funasaki, Suguru
    ;
    Iwasaki, Ryuhei
    ;
    Yoshitake, Tsuyoshi
    N-Type nanocrystalline FeSi<inf>2</inf>/intrinsic Si/p-type Si heterojunctions were successfully fabricated by FTDCS and their forward current-voltage characteristics at low temperatures were analyzed on the basis of thermionic emission theory. The analysis of J-V characteristics exhibits an increase in the ideality factor and a decrease in the barrier height at low temperatures. The values of ideality factor were estimated to be 2.26 at 300 K and 9.29 at 77 K. The temperature dependent ideality factor together with the constant value of parameter A indicated that a trap assisted multistep tunneling process is the dominant carrier transport mechanism in this heterojunction. At high voltages, the current transport mechanism is dominated by SCLC process. © (2013) Trans Tech Publications, Switzerland.