Akademik Veri Yönetim Sistemi
International Journal of Modern Physics B, 2026 (SCI-Expanded, Scopus)
This study examines the frequency- and voltage-dependent electrical parameters, interface trap densities (Dit) and relaxation times (τ) in Au/PVA:(CoFe2O4-rGO)/n-Si structures using three complementary admittance methods. CoFe2O4 nanoparticles, synthesized hydrothermally, were incorporated with reduced graphene oxide (rGO) into polyvinyl alcohol (PVA) matrices and spin-coated onto n-Si substrates to form interfacial layers. Capacitance–voltage (C–V) and conductance–voltage (G/ω–V) measurements spanned −2.0–+3.0V across 0.3kHz–3MHz. Pronounced frequency dispersion was observed: forward-bias capacitance at +3.0V fell from ∼9nF (0.3kHz) to ∼2.5nF (3MHz), while the normalized conductance peaked near 0.8–1.0V at all frequencies, with trap saturation above ∼0.75V. Hill–Coleman analysis revealed Dit values that decline quasi-exponentially from ∼1.3×1014 eV−1 cm−2 at low frequencies to ∼1.0×1013 eV−1 cm−2 at high frequencies. Parallel-conductance extraction revealed τ spanning three orders of magnitude, from ∼120 μs at 0.20V to ∼0.08 μs at 1.60V, with the normalized conductance saturating above ∼0.75V, consistent with strong field-induced acceleration of trap dynamics and near-complete filling of accessible trap levels under moderate forward bias. This behavior arises because the AC period shortens relative to τ: once the period falls below the trap response time, slower states cease contributing to the measured admittance. The apparent donor concentration decreased from ∼2.15×1017 cm−3 to ∼7.7×1015 cm−3 over the same frequency range, while the depletion width expanded from 6.6μm to 39.9μm, and the peak electric field diminished from ∼2.17×105 V/cm to ∼4.75×104 V/cm over the same frequency. Unlike conventional low-dielectric interlayers that cannot fully suppress interface states or reduce series resistance, the high-dielectric PVA:(CoFe2O4-rGO) nanocomposite studied here offers a broader operating window by neutralizing a substantial fraction of Nss while regulating charge transport mechanisms. To our knowledge, this is the first frequency-resolved, multi-method mapping of Dit and τ distributions in such a system, offering practical guidance for engineering nanocomposite interlayers with tailored trap spectra.