On the frequency dependent negative dielectric constant behavior in Al/Co-doped (PVC+TCNQ)/p-Si structures

Abstract

The dielectric properties, electric modulus and ac electrical conductivity (σac) of Al/Codoped (PVC + TCNQ)/p-Si structures have been investigated in the wide frequency and voltage range of 0.5 kHz-3 MHz and (−4 V)-(9 V), respectively, using the capacitancevoltage (C-V ) and conductance-voltage (G/ω-V ) measurements at room temperature. The real and imaginary parts of dielectric constant (ε ′ , ε ′′ ), loss tangent (tan δ), σac and the real and imaginary parts of electric modulus (M ′ , M ′′ ) were found strongly function of frequency and applied voltage especially at low frequencies. The ε ′ -V plot shows an anomalous peak in the forward bias region due to the series resistance (Rs), surface states (Nss) and interfacial layer (PVC + TCNQ) effects for each frequency and then it goes to negative values known as negative dielectric constant (NDC) at low frequencies (f ≤ 70 kHz). Such observation of NDC is important result because it implies that an increment of bias voltage produces a decrease in the charge on the electrodes. The amount of negativity ε ′ value increases with decreasing frequency and this decrement in the NDC corresponds to the increment in the ε ′′ .

The effects of Bi4Ti3O12 interfacial ferroelectric layer on the dielectric properties of Au/n-Si structures

“…Another dielectric parameter that is often considered in these type of structures is the loss tangent (tan δ) which is given by [20][21][22][23][24][25][26][27][28][29] using the values of capacitance and conductance (which depend on bias voltage by exhibiting inversion, depletion and accumulation regions with increasing voltage), they show dependence on bias voltage. ε ′ , ε ′′ and tan δ were found to be strong functions of voltage and frequency especially at forward positive voltages and low frequencies.…”

“…30,31 Hence, dielectric relaxation spectroscopy data are also used in the electric modulus formalism in order to extract as much information as possible. [22][23][24][25][26][27][28][30][31][32][33] The electric modulus has been used by many researchers to analyze and interpret electrical relaxation data of wide variety of materials. [22][23][24][25][26][27][28][30][31][32][33][34] Thus, the evaluation of the electric modulus as a function of frequency permits to detect the presence of relaxation processes in the studied materials.…”

“…[22][23][24][25][26][27][28][30][31][32][33] The electric modulus has been used by many researchers to analyze and interpret electrical relaxation data of wide variety of materials. [22][23][24][25][26][27][28][30][31][32][33][34] Thus, the evaluation of the electric modulus as a function of frequency permits to detect the presence of relaxation processes in the studied materials. In order to study dielectric dispersion in the MS and MFS structures, the complex electric modulus (M * ) which is defined by following relation is used, [22][23][24][25][26][27][28][30][31][32][33][34][35] …”

Current-transport mechanism in Au/V-doped PVC+TCNQ/p-Si structures

“…8,11 The existence of such thin insulator/polymer layer between metal and semiconductor converts the metal-semiconductor (MS) diode to the metal-insulator/polymer-semiconductor (MIS or MPS) type Schottky barrier diodes (SBDs) and may have strong influence on the diode characteristics. [12][13][14][15][16][17][18][19][20][21][22] The analysis of the current-voltage (I-V ) characteristics in these diodes only at room temperature do not give detailed information on the possible currenttransport mechanisms (CTMs) and the nature of barrier height (BH) formation at MS interface. These measurements carried out in the wide temperature range can allow us to understand various aspects of CTMs and the nature of barrier formation.…”

On the Anomalous Peak in the Forward Bias Capacitance and Dielectric Properties of the Al/Co-Doped (PVC + TCNQ)/p-Si structures as Function of Temperature

“…[1][2][3][4][5][6][7][8][9][10] When the use of an insulator such as polymer and ferroelectric interfacial layer (TiO 2 , PVA, and Bi 3 Ti 4 O 12 ), MS structure converts to metal-insulator-semiconductor (MIS), metalpolymer-semiconductor (MPS) and metal-ferroelectricsemiconductor (MFS) type structures. 11 12 The existence such an interfacial layer, both the C-V and G/ − V * Author to whom correspondence should be addressed.…”