Vol.:(0123456789) 1 3 Applied Physics A (2018) 124:275 https://doi.org/10.1007/s00339-018-1684-4 Frequency- and doping-level infuence on electric and dielectric properties of PolySi/SiO 2 /cSi (MOS) structures N. Doukhane 1  · B. Birouk 1 Received: 27 August 2017 / Accepted: 14 February 2018 © Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract The electric and dielectric characteristics of PolySi/SiO 2 /cSi (MOS) structure, such as series resistance (R s ), dielectric constants (ɛ′) and (ɛ″), dielectric losses (tan δ), and the ac electric conductivity (σ ac ), were studied in the frequency range 100 kHz–1 MHz for various doping levels and two thicknesses for the polysilicon layer (100 and 175 nm). The experimental results show that the C and G/ω characteristics are very sensitive to the frequency due to the presence of interface states. Series resistance R s is deduced from C and G/ω measurements and is plotted as a function of the frequency for various doping levels. It is found to decrease with frequency and doping level. To determine   , ε″, tan δ, and  ac , the admittance technique was used. An interesting behavior of the constants,   and ε″, was noticed. The   values ft led to relations between   and the frequency, on one hand, and between   and the electric conductivity of the polysilicon layers on the other. These relations make it possible to interpolate directly between two experimental points for a given frequency. The analysis of the results shows that the values of   , ε″, and tan δ decrease with increasing frequency. This is due to the fact that in the region of low frequencies, interfacial polarization occurs easily, and the interface states between Si and SiO 2 contribute to the improvement of the dielectric properties of the PolySi/SiO 2 /cSi structures. The study also emphasizes that the ac electric conductivity increases with the increase in frequency and doping level; this causes to the reduction in series resistance. 1 Introduction The MOS structure consists in the stacking of three layers: single-crystal silicon substrate on which an oxide layer has been grown and a metal electrode gate. The thickness of the oxide layer generally varies from few to hundreds of nanom- eters. However, the objective of the researchers is to make it as thinner as possible to reduce the size of the components. Due to the presence of oxide layer and two surface-charge regions, MOS physics is more complicated than semicon- ductor surface physics [1, 2]. In real MOS structure, the localized interface states are located between the semicon- ductor and the insulator. The behavior of the device difers from the ideal case as a consequence of the presence of these interface states. In general, one distinguishes several pos- sible sources of error, causing deviations of the behavior of the ideal MOS such as the electric and dielectric properties, to name a few, and which must be taken into account [3]. Because of the presence of the localized loads (P + ) and impurities (Cl − , S − , F − , O − , C − , H − ) in the dielectric layer, or the presence of the interface states (incomplete links) and series resistance at the interface between the dielectric layer and the semiconductor, the behavior of MOS devices is very diferent from the classical condensers. These difer- ences may be due to fabrication process, defects of the lattice structure at the interfacial layer, in the semiconductor and dielectric layers [4–6]. The electric characteristics of these devices are extremely sensitive to interface states density at the oxide/monosilicon interface [7, 8]. C–V and G–V measurements give several important informations upon electric and dielectric characteristics of the MOS structures. In this study, the use of C–V and G–V measurements enabled us to understand the frequency response of the PolySi/SiO 2 /cSi MOS structure by varying the frequency in the range of 100 kHz–1 MHz. Moreo- ver, to achieve a better understanding of the doping-level efects, we took into account this parameter in the electric and dielectric properties’ study of PolySi/SiO 2 /cSi struc- tures, by considering various phosphorus concentrations * N. Doukhane doukhanen@yahoo.com B. Birouk bbirouk@gmx.com 1 Renewable Energies Laboratory (LER), Electronics Department, FST, Jijel University, Jijel, Algeria