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Electrons in Semiconductors
Published in Hualin Zhan, Graphene-Electrolyte Interfaces, 2020
Capacitor is one of the most important electrical elements in electronic devices. Quantum capacitance (Cq), an intrinsic property, of capacitors made of semiconductors plays a critical role when the size of the capacitors reduces into nanoscales. This concept is introduced in semiconductor physics while studying transistors (as the gate capacitance defines the number of charge carriers in the conducting channel) [Luryi (1988); Szkopek (2013)].
The Chemical Capacitance
Published in Juan Bisquert, The Physics of Solar Energy Conversion, 2020
In semiconductor devices that include very narrow layers, showing strong quantization effects, the (chemical) capacitance associated with adding carriers to the band structure of the semiconductor, is called the quantum capacitance. This denomination is, of course, appropriate because the electrons are put into quantum states, when the electrochemical potential is modified.
Empirical Drain Current Model of Graphene Field-Effect Transistor for Application as a Circuit Simulation Tool
Published in IETE Journal of Research, 2022
Sudipta Bardhan, Manodipan Sahoo, Hafizur Rahaman
The excellent properties of graphene encourage the researchers for implementing the high-quality analog electronic circuits [1–3]. It is a mono atomic 2D structure [4] with high electron mobility. At room temperature, the mobility is 2 × 10−5 cm2/V.s [5]. Its saturation velocity is also high approximately 6.3 × 107 cm/s [6]. Graphene-based multipliers and mixers in [7,8], ultra broadband photo detector [9], terahertz modulator [10] have been presented previously. Compact models of graphene FET are generally classified as physical models or empirical models. Several graphene-based physical models have been reported in [11–14]. Empirical models are designed for standard EDA tools. A quasi-analytical model of graphene FET has been reported in [15]. A drift-diffusion approach has been taken in [16] to achieve drain current expression explicitly. In [17], a GFET model has been presented considering a virtual source approach to obtain device performance. A Boltzmann transport approach-based analytical GFET model is proposed in [18] assuming the optical phonon scattering, acoustic phonon scattering, and carrier-carrier scattering effects. In [19], a scalable electrical model of GFET has been presented. A dual gate bilayer and four-layer GFET model is proposed with circuit design in [11]. An accurate drift-diffusion model, compatible with Verilog-A, is discussed in [20]. In [21], a charge-based model is developed using a virtual source technique for short channel graphene. Improved carrier mobility analysis of SPICE-like GFET is presented in [22]. However, several physical parameters are responsible for simplifying the complexity of these types of compact models of GFET like, (i) Quantum capacitance, (ii) electrostatic capacitance of gate, (iii) carrier density in channel, (iv) saturation velocity, (v) surface potential in channel, (vi) parasitic resistances at the contact region, (vii) inaccuracy at Dirac point due to small channel potential.