The origin of constant phase element in equivalent circuit of MIS ( n ) GaAs structures
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The origin of constant phase element in equivalent circuit of MIS (n) GaAs structures Łukasz Drewniak1,* 1
and Stanisław Kochowski1
Institute of Physics – Centre for Science and Education, Silesian University of Technology, Konarskiego 22B, 44-100 Gliwice, Poland
Received: 15 July 2020
ABSTRACT
Accepted: 5 September 2020
The Au/Pd/Ti–SiO2-(n) GaAs properties have been analyzed via impedance spectroscopy (IS), as well as DLTS and ICTS, to identify the origin of electron processes responsible for existence of constant phase elements (CPE) in an equivalent circuits of that structure. We showed that CPEs connected in series with resistance represents the electron processes associated with deep levels in GaAs and/or interface states at SiO2-(n) GaAs interface, depending on the value of n of CPE parameter. CPE with n close to 1 characterize the electron processes associated with EL2 deep level, and CPE with n = 0.5–0.65 the complex electron processes associated with EL3 deep level and interface states together. We stated that constant phase elements in equivalent circuits of MIS-GaAs structures with large frequency dispersion of electrical characteristics can be the result of more than one electron process.
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The Author(s) 2020
1 Introduction The metal–insulator-semiconductor (MIS) and the metal–oxide–semiconductor (MOS) structures are both the basic components of complex electronic systems and good tool for characterizing the insulator-semiconductor (I-S) interface properties of different materials. The use of MIS/MOS structures in electronics strongly depends on their I-S interface properties, which are determined by the localized electronic states (interface states) and semiconductor bulk states (deep states). It is well known that the high density of interface states prevent for a long time a fabrication of field effect devices based on III–V semiconductor compounds in 90s. However, since the beginning of the twenty-first century, renewed Address correspondence to E-mail: [email protected]
https://doi.org/10.1007/s10854-020-04447-8
interest in such devices has been observed [1–15]. It is associated with the development of new passivation technologies, the construction of new metal–insulator-semiconductor field effect transistors (MISFET), and a number of issues related to silicon device scaling [16–18]. In general, the MIS/MOS capacitance and conductance measurements, vs. gate voltage and frequency, can be used to characterize electron processes at the I-S interface and determination of interfacial parameters [19]. Unfortunately, these measurements cannot be simply used in MIS-GaAs systems because of many peculiarities observed in their electrical characteristics, including the large capacitance and conductance frequency dispersion,
J Mater Sci: Mater Electron
hysteresis effects, Fermi level pinning, and difficulties in recording high-frequency characteristics [20–23]. In systems with a large frequency dispersion of electrical characteristics, the impedance spectroscopy is widely used. The idea o
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