Surface states and series resistance effects in Au/(HgS-PVA)/n-Si capacitors

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Abstract HgS nanomaterials were synthesized using an ultrasound-assisted method, and their optical and morphological properties were analyzed through UV–Vis spectroscopy and scanning electron microscopy (SEM). The capacitance–voltage (C–V) and conductance–voltage (G/ω–V) measurements of the Au/(HgS-PVA)/n-Si (MPS) capacitor were conducted across a frequency range of 1 kHz–5 MHz. The experimental data were used to investigate the effects of surface states (N ss) and series resistance (R s). Both C and G/ω increased at lower frequencies, as the surface states could follow the AC signal, contributing to the overall response. The density of N ss was derived using the high-low frequency (HF) capacitance method and parallel conductance technique, while Nicollian–Brews’ method was employed to extract the R s. This study reveals that the conductance method yields higher values than the HF C–V method, attributed to its sensitivity to fast interface states and distributed trap time constants. The observed frequency-dependent losses in G p/ω measurements confirm the presence of a continuous trap distribution near the HgS-PVA/n-Si surface, significantly influencing device reliability. The average N ss was calculated to be ~ 1012 eV⁻1 cm⁻2, indicating a well-controlled interface. The obtained N ss and R s values suggest that the HgS-PVA nanocomposite is a promising alternative to conventional insulating layers (e.g., SiO₂ or SnO₂) in electronic devices, thanks to its favorable electrical properties.