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<p>Au/PMI/n-GaAs/In metal–organic-semiconductor (MOmS) Schottky diodes were prepared and systematically characterized by frequency-dependent dielectric and impedance measurements under applied bias voltages ranging from 0 to 2&#xa0;V at room temperature. The frequency-dependent capacitance and conductance results showed significant dispersion at low frequencies due to interfacial polarization and trap-assisted relaxation processes. The real and imaginary parts of the dielectric permittivity exhibited strong bias dependence, revealing the effect of the electric field on charge dynamics at the perylene monoimide (PMI)/GaAs interface. The loss tangent (tan<i>δ</i>) spectra exhibited a single distinct relaxation peak, from which <i>fmax</i> and <i>τ</i> were extracted. The decrease of <i>τ</i> with increasing bias indicates field-assisted enhancement of localized charge motion. The AC conductivity followed Jonscher’s universal power law with a small frequency exponent (s ≈ 0.02–0.05), indicating weakly dispersive, nearly frequency-independent transport with only a small localized-hopping contribution. The impedance spectra were successfully described using the equivalent circuit Rs–(Rg || CPEg)–CPEtail, with good agreement between experimental and fitted data. Nyquist plots did not exhibit an ideal, complete semicircular structure within the measured voltage range. Instead, flattened and incomplete impedance curves were obtained. This finding suggests that the system does not behave as an ideal RC circuit and that the capacitive response exhibits a distributed character. The observed deviation from ideal Debye-type behavior indicates that relaxation times within the structure exhibit a certain distribution. AFM measurements revealed nanoscale surface roughness of the PMI interlayer and supported the non-ideal capacitive behavior observed in the impedance analysis. The results indicate that the PMI interlayer plays an effective role in tuning interfacial polarization, relaxation dynamics, and AC transport mechanisms in Au/PMI/n-GaAs/In Schottky structures.</p>

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Bias-dependent dielectric relaxation and impedance analysis of Au/PMI/n-GaAs/In MOmS Schottky structures

  • 期刊论文

  • 发表日期：

    2026年7月2日

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  • Nihat Tuğluoğlu,
  • Zeynep Kişnişci,
  • Serkan Eymur,
  • Pınar Oruç

摘要

Au/PMI/n-GaAs/In metal–organic-semiconductor (MOmS) Schottky diodes were prepared and systematically characterized by frequency-dependent dielectric and impedance measurements under applied bias voltages ranging from 0 to 2 V at room temperature. The frequency-dependent capacitance and conductance results showed significant dispersion at low frequencies due to interfacial polarization and trap-assisted relaxation processes. The real and imaginary parts of the dielectric permittivity exhibited strong bias dependence, revealing the effect of the electric field on charge dynamics at the perylene monoimide (PMI)/GaAs interface. The loss tangent (tanδ) spectra exhibited a single distinct relaxation peak, from which fmax and τ were extracted. The decrease of τ with increasing bias indicates field-assisted enhancement of localized charge motion. The AC conductivity followed Jonscher’s universal power law with a small frequency exponent (s ≈ 0.02–0.05), indicating weakly dispersive, nearly frequency-independent transport with only a small localized-hopping contribution. The impedance spectra were successfully described using the equivalent circuit Rs–(Rg || CPEg)–CPEtail, with good agreement between experimental and fitted data. Nyquist plots did not exhibit an ideal, complete semicircular structure within the measured voltage range. Instead, flattened and incomplete impedance curves were obtained. This finding suggests that the system does not behave as an ideal RC circuit and that the capacitive response exhibits a distributed character. The observed deviation from ideal Debye-type behavior indicates that relaxation times within the structure exhibit a certain distribution. AFM measurements revealed nanoscale surface roughness of the PMI interlayer and supported the non-ideal capacitive behavior observed in the impedance analysis. The results indicate that the PMI interlayer plays an effective role in tuning interfacial polarization, relaxation dynamics, and AC transport mechanisms in Au/PMI/n-GaAs/In Schottky structures.