Temperature and frequency dependent electrical and dielectric properties of Al/SiO2/p-Si (MOS) structure

The electrical and dielectric properties of Al/SiO₂/p-Si (MOS) structures were studied in the frequency range 10 kHz-10 MHz and in the temperature range 295-400 K. The interfacial oxide layer thickness of 320 Å between metal and semiconductor was calculated from the measurement of the oxide capacitance in the strong accumulation region. The frequency and temperature dependence of dielectric constant (ε′), dielectric loss (ε″), dielectric loss tangent (tan δ) and the ac electrical conductivity (σ_ac) are studied for Al/SiO₂/p-Si (MOS) structure. The electrical and dielectric properties of MOS structure were calculated from C-V and G-V measurements. Experimental results show that the ε′ and ε″ are found to decrease with increasing frequency while σ_ac is increased, and ε′, ε″, tan δ and σ_ac increase with increasing temperature. The values of ε′, ε″ and tan δ at 100 kHz were found to be 2.76, 0.17 and 0.06, respectively. The interfacial polarization can be more easily occurred at low frequencies, and the number of interface state density between Si/SiO₂ interface, consequently, contributes to the improvement of dielectric properties of Al/SiO₂/p-Si (MOS) structure. Also, the effects of interface state density (N_ss) and series resistance (R_s) of the sample on C-V characteristics are investigated. It was found that both capacitance C and conductance G were quite sensitive to temperature and frequency at relatively high temperatures and low frequencies, and the N_ss and R_s decreased with increasing temperature. This is behavior attributed to the thermal restructuring and reordering of the interface. The C-V and G/ω-V characteristics confirmed that the N_ss, R_s and thickness of insulator layer (δ) are important parameters that strongly influence both the electrical and dielectric parameters and conductivity in MOS structures.     

Frequency and gate voltage effects on the dielectric properties of Au/SiO2/n-Si structures

To determine the dielectric constant (ε′), dielectric loss (ε″), loss tangent (tan δ), the ac electrical conductivity (σ_ac) and the electric modulus of Au/SiO₂/n-Si structure, the measurement admittance technique was used. Experimental results show that the values of ε′, ε″, tan δ, σ_ac and the electric modulus show fairly large frequency and gate bias dispersion especially at low frequencies due to the interface charges and polarization. An increase in the values of the ε′ and ε″ were observed with both a decrease in frequency and an increase in frequency. The σ_ac is found to increase with both increasing frequency and voltage. In addition, the experimental dielectrical data have been analyzed considering electric modulus formalism. It can be concluded that the interface charges and interfacial polarization have strong influence on the dielectric properties of metal-insulator-semiconductor (MIS) structures especially at low frequencies and both in depletion and accumulation regions.     

Temperature dependent electrical and dielectric properties of Sn/p-Si metal-semiconductor (MS) structures

In this study, we investigated temperature dependent electrical and dielectric properties of the Sn/p-Si metal-semiconductor (MS) structures using capacitance-voltage (C-V) and conductance-voltage (G/ω-V) characteristics in the temperature range 80-400 K. The dielectric constant (ε′), dielectric loss (ε′′), dielectric loss tangent (tan δ) and ac electrical conductivity (σ_ac) were calculated from the C-V and G/ω-V measurements and plotted as a function of temperature. The values of the ε′, ε′′, tan δ and σ_ac at low temperature (=80 K) were found to be 0.57, 0.37, 0.56 and 1.04 × 10⁻⁷, where as the values of the ε′, ε′′, tan δ and σ_ac at high temperature (=400 K) were found to be 0.75, 0.44, 0.59 and 1.21 × 10⁻⁶, respectively. An increase in the values of the ε′, ε′′, tan δ and σ_ac where observed with increase in temperature. Furthermore, the effects of interface state density (N_SS) and series resistance (R_S) on C-V characteristics were investigated in the wide temperature range.     

Dielectric properties and ac electrical conductivity studies of MIS type Schottky diodes at high temperatures

Dielectric properties and ac electrical conductivity of the Al/SiO₂/p-Si (MIS) Schottky diodes were studied in the frequency and temperature range of 10 kHz-1 MHz and 300-400 K, respectively. Experimental results show that the dielectric constant (ε′), dielectric loss (ε″), loss tangent (tan δ), ac electrical conductivity (σ_ac) and the electric modulus were found a strong function of frequency and temperature. The values of the ε′, ε″ and tan δ decrease with increasing frequencies due to the interface states capacitance and a decrease in conductance with increasing frequency. Also, these values increase with increasing temperature. The σ_ac is found to increase with increasing frequency and increasing temperature. The variation of conductivity as a function of temperature and frequency reveals non-adiabatic hopping of charge carriers between impurities localized states. In addition, the experimental dielectric data have been analyzed by considering electric modulus formalism.     

Temperature dependent electrical and dielectric properties of Au/polyvinyl alcohol (Ni, Zn-doped)/n-Si Schottky diodes

The electrical and dielectric properties of Au/PVA (Ni, Zn-doped)/n-Si Schottky diodes (SDs) were studied in the temperature range of 80-400 K. The investigation of various SDs fabricated with different types of interfacial layer is important for understanding the electrical and dielectric properties of SDs. Therefore, in this study polyvinyl alcohol (PVA) film was used as an interfacial layer between metal and semiconductor. The electrical and dielectric properties of Au/PVA (Ni, Zn-doped)/n-Si SDs were calculated from the capacitance-voltage (C-V) and conductance-voltage (G/w-V) measurements. The effects of interface state density (N_ss) and series resistance (R_s) on C-V characteristics were investigated in the wide temperature range. It was found that both of the C-V-T and G/w-V-T curves included two abnormal regions and one intersection point. The dielectric constant (ε″), dielectric loss (ε″), dielectric loss tangent (tan δ) and the ac electrical conductivity (σ_ac) obtained from the measured capacitance and conductance were studied for Au/PVA (Ni, Zn-doped)/n-Si SDs. Experimental results show that the values of ε′, ε″ and tan δ are a strong function of the temperature. Also, the results indicate the interfacial polarization can be more easily occurred at high temperatures.     

Dielectric properties in Au/SnO2/n-Si (MOS) structures irradiated under Co-γ rays

The metal-oxide-semiconductor (MOS) structures with insulator layer thickness range of 55-430 Å were stressed with a bias of 0 V during ⁶⁰Co-γ ray source irradiation with the dose rate of 2.12 kGy/h and the total dose range was 0-5×10⁵ Gy. The real part of dielectric constant ε′, dielectric loss ε″, dielectric loss tangent tanδ and the dc conductivity σ_dc were determined from against frequency, applied voltage, dose rate and thickness of insulator layer at room temperature for Au/SnO₂/n-Si (MOS) structures from C-V capacitance and G-V conductance measurements in depletion and weak inversion before and after irradiation. The dielectric properties of MOS structures have been found to be strongly influenced by the presence of dominant radiation-induced defects. The frequency, applied voltage, dose rate and thickness dependence of ε′, ε″, tanδ and σ_dc are studied in the frequency (500 Hz-10 MHz), applied voltage (−10 to 10 V), dose rate (0-500 kGy) and thickness of insulator layer (55-430 Å) range, respectively. In general, dielectric constant ε′, dielectric loss ε″ and dielectric loss tangent are found to decrease with increasing the frequency while σ_dc is increased. Experimental results shows that the interfacial polarization can be more easily occurred at the lower frequency and/or with the number of density of interface states between Si/SnO₂ interfaces, consequently, contribute to the improvement of dielectric properties of Au/SnO₂/n-Si (MOS) structures.     

Frequency and temperature dependent dielectric properties of Al/Si3N4/p-Si(1 0 0) MIS structure

The dielectric properties of Al/Si₃N₄/p-Si(1 0 0) MIS structure were studied from the C-V and G-V measurements in the frequency range of 1 kHz to 1 MHz and temperature range of 80-300 K. Experimental results shows that the ε′ and ε″ are found to decrease with increasing frequency while the value of ε′ and ε″ increase with increasing temperature, especially, above 160 K. As typical values, the dielectric constant ε′ and dielectric loss ε″ have the values of 7.49, 1.03 at 1 kHz, and only 0.9, 0.02 at 1 MHz, respectively. The ac electrical conductivity (σ_ac) increases with both increasing frequency and temperature. The activation energy of 24 meV was calculated from Arrhenius plot at 1 MHz. The results indicate that the interfacial polarization can be more easily occurred at low frequencies and high temperatures.     

Study on the frequency dependence of electrical and dielectric characteristics of Au/SnO2/n-Si (MIS) structures

In this paper, we present a detailed investigation of the electrical and dielectric properties of the Au/SnO₂/n-Si (MIS) structures. The capacitance-voltage (C-V) and conductance-voltage (G/ω-V) characteristics have been measured in the frequency range of 1 kHz-1 MHz at room temperature. Calculation of the dielectric constant (?′), dielectric loss (?″), loss tangent (tan δ), ac electrical conductivity (σ_ac), ac resistivity (ρ_ac) and the electric modulus are given in the studied frequency ranges. Experimental results show that the values of dielectric parameters are a strong function of frequency. The decrease of ?′ and ?″ with increasing frequency were observed. In addition the increase of σ_ac with increasing frequency is founded. Also, electric modulus formalism has been analyzed to obtain the experimental dielectric data. The interfacial polarization can be more easily occurred at the lower frequency and/or with the number of interface state density between SnO₂/Si interface, consequently, contribute to the improvement of dielectric properties of MIS structure.     

Frequency and voltage effects on the dielectric properties and electrical conductivity of Al-TiW-Pd2Si/n-Si structures

Different from conventional metal-Si compounds-n-Si structures, the thin film of TiW alloy was deposited on Pd₂Si-n-Si to form a diffusion barrier between aluminum (Al) and Pd₂Si-n-Si. Dielectric properties and electrical conductivity of TiW-Pd₂Si/n-Si structures in the frequency range of 5 kHz-10 MHz and voltage range of (−4 V) to (10 V) have been investigated in detail by using experimental C-V and G-V measurements. Experimental results indicate that the values of ε′ show a steep decrease with increasing frequency for each voltage. On the other hand, the values of ε″ show a peak, and its intensity increases with decreasing voltage and shifts towards the lower frequency side. The ac electrical conductivity (σ_ac) and the real part of electric modulus (M′) increase with increasing frequency. Also, the imaginary part of electric modulus (M″) shows a peak and the peak position shifts to higher frequency with increasing applied voltage. It can be concluded that the interfacial polarization can be more easily occurred at low frequencies, and the majority of interface states at metal semiconductor interface, consequently contributes to deviation of dielectric properties of TiW-Pd₂Si/n-Si structures.     

On the profile of frequency dependent series resistance and dielectric constant in MIS structure

In this study, the frequency dependent of the forward and reverse bias capacitance-voltage (C-V) and conductance-voltage (G/ω - V) measurements of Al/SiO₂/p-Si (MIS) structures are carried out in frequency range of 10 kHz-10 MHz. The frequency dependence of series resistance (R_s), density of surface states (N_ss), dielectric constant (ε′), dielectric loss (ε″), dielectric loss tangent (tan δ) and the ac electrical conductivity (σ_dc) are studied for these structure at room temperature. Experimental results show that both electrical and dielectric parameters were strongly frequency and voltage dependent. The ε′ and ε″ are found to decrease with increasing frequency while σ_ac is increased. Also, both the effects of surface states N_ss and R_s on C-V and G/ω - V characteristics are investigated. It has been seen that the measured C and G decrease with increasing frequency due to a continuous distribution of N_ss in frequency range of 10 kHz-1 MHz. The effect of R_s on the C and G are found noticeable at high frequencies. Therefore, the high frequencies C and G values measured under both reverse and forward bias were corrected for the effect of series resistance R_s to obtain real MIS capacitance C_c and conductance G_c using the Nicollian and Goetzberger technique. The distribution profile of R_s-V gives a peak in the depletion region at low frequencies and disappears with increasing frequencies.     

Dielectric spectroscopy studies on (PVP + PVA) polyblend film

The thermal behavior of (PVP + PVA) polyblend film have been examined using differential scanning calorimetry and scanning electron microscopy. Capacitance and loss tangent values of polyvinyl pyrrolidone (PVP) + polyvinyl alcohol (PVA) polyblend film were measured in the frequency range 1-100 kHz and temperature range 298-423 K. Dielectric permittivity of real part (ε′) was obtained from capacitance data and dielectric permittivity of imaginary part (ε″) was obtained from real part of dielectric permittivity and loss tangent values. The decrease in dielectric permittivity was observed with increasing frequency and also observed increase in dielectric permittivity with increasing temperature. The complex dielectric constant (ε*) has been described by the electric modulus M* = (1/ε*) = M′ + iM″. The data of M* has been analysed by the stretched exponential decay of the electric field, Φ(t) = exp−(t/τ₀)^β.     

Frequency and temperature dependence of the dielectric and AC electrical conductivity in (Ni/Au)/AlGaN/AlN/GaN heterostructures

The dielectric properties and AC electrical conductivity (σ_ac)of the (Ni/Au)/Al_0.22Ga_0.78N/AlN/GaN heterostructures, with and without the SiN_x passivation, have been investigated by capacitance-voltage and conductance-voltage measurements in the wide frequency (5kHz-5 MHz) and temperature (80-400 K) range. The experimental values of the dielectric constant (ε′), dielectric loss (ε′′), loss tangent (tanδ), σ_ac and the real and imaginary part of the electric modulus (M′ and M′′) were found to be a strong function of frequency and temperature. A decrease in the values of ε′ and ε′′ was observed, in which they both showed an increase in frequency and temperature. The values of M′ and M′′ increase with increasing frequency and temperature. The σ_ac increases with increasing frequency, while it decreases with increasing temperature. It can be concluded, therefore, that the interfacial polarization can occur more easily at low frequencies and temperatures with the number of interface states density located at the metal/semiconductor interface. It contributes to the ε′ and σ_ac.     

Temperature dependent dielectric studies of Ni/n-GaP Schottky diodes by capacitance and conductance measurements

The dielectric properties of Ni/n-GaP Schottky diode were investigated in the temperature range 140–300 K by capacitance–voltage (C–V) and conductance–voltage (G/ω–V) measurements. The effect of temperature on series resistance (R_s) and interface state density (N_ss) were investigated. The dependency of dielectric constant (ε′), dielectric loss (ε′′), loss tangent (tan δ), ac conductivity (σ_ac), real (M′) and imaginary (M′′) parts of the electric modulus over temperature were evaluated and analyzed at 1 MHz frequency. The temperature dependent characteristics of ε′ and ε′′ reveal the contribution of various polarization effects, which increases with temperature. The Arrhenius plot of σ_ac shows two activation energies revealing the presence of two distinct trap states in the chosen temperature range. Moreover, the capacitance–frequency (C–f) measurement over 1 kHz to 1 MHz was carried out to study the effect of localized interface states.     

Dielectric Properties of Au/PVA (Cobalt-Doped)/n-Si Photoconductive Diodes

The voltage (V) and frequency (f) dependence of dielectric parameters such as the dielectric constant (ε′), dielectric loss (ε″), dielectric loss tangent (tan δ), real and imaginary parts of electrical modulus (M′ and M″), and alternating-current (AC) electrical conductivity (σ _AC) of Au/PVA (cobalt-doped)/n-Si structures have been investigated by using experimental admittance measurements conducted at room temperature. The values of ε′, ε″, and tan δ were found to be strong functions of voltage and frequency, especially at low frequencies in the positive voltage region. It was observed that the values of ε′ and ε″ increase as the frequency decreases. The M′ values increase with increasing frequency due to increasing dielectric relaxation, while M″ values, in general, remain stable as frequency is changed. The σ _AC values at each bias voltage increase with increasing frequency.     

Frequency and voltage dependence of negative capacitance in Au/SiO2/n-GaAs structures

The frequency (f) and bias voltage (V) dependence of electrical and dielectric properties of Au/SiO₂/n-GaAs structures have been investigated in the frequency range of 10 kHz–3 MHz at room temperature by considering the presence of series resistance (R_s). The values of R_s, dielectric constant (ε′), dielectric loss (ε″) and dielectric loss tangent (tan δ) of these structures were obtained from capacitance–voltage (C–V) and conductance–voltage (G/ω–V) measurements and these parameters were found to be strong functions of frequency and bias voltage. In the forward bias region, C–V plots show a negative capacitance (NC) behavior, hence ε′–V plots for each frequency value take negative values as well. Such negative values of C correspond to the maximum of the conductance (G/ω). The crosssection of the C–V plots appears as an abnormality when compared to the conventional behavior of ideal Schottky barrier diode (SBD), metal–insulator–semiconductor (MIS) and metal–oxide–semiconductor (MOS) structures. Such behavior of C and ε′ has been explained with the minority-carrier injection and relaxation theory. Experimental results show that the dielectric properties of these structures are quite sensitive to frequency and applied bias voltage especially at low frequencies because of continuous density distribution of interface states and their relaxation time.     

Dielectric characteristics of gamma irradiated Au/SnO2/n-Si/Au (MOS) capacitor

The dielectric characteristics of gamma irradiated Au/SnO₂/n-Si/Au (MOS) capacitor were studied. The MOS capacitor was irradiated by a ⁶⁰Co gamma radiation source with a dose rate of 0.69 kGy/h. The dielectric parameters such as dielectric constant (ε′), dielectric loss (ε″), loss factor (tan δ) and ac electrical conductivity (σ_ac) were calculated from the capacitance–voltage (C–V) and conductance–voltage (G/ω–V) measurements. It is found that the C and G/ω values decrease with the increasing total dose due to the irradiation-induced defects at the interface. Also, the calculated values of ε′, ε″ and σ_ac are found to decrease with an increased radiation dose. This result indicates that the dielectric characteristics of the MOS capacitor are sensitive to gamma-ray dose.     

Frequency and voltage dependence of admittance characteristics of Al/Al2O3/PVA:n-ZnSe Schottky barrier diodes

This paper reports the frequency dependence of admittance measurements i.e C–V and G/ω–V characteristics of Al/Al₂O₃/PVA:n-ZnSe MIS diode. The interface states (N_ss) and series resistance (R_s) of the MIS diode strongly influence the C–V–f and G/ω–V–f characteristics. The conductance method is used to calculate the series resistance (R_s), the density of states (N_ss), insulator layer capacitance and thickness. The frequency dependent dieclectric parameters such as dielectric constant (εʹ), dielectric loss (ε″), loss tangent (tan δ) and a.c. electrical conductivity (σ_ac) has been calculated and which are also responsible for observed frequency dispersion in C–V and G/ω curves.     

On the energy distribution of interface states and their relaxation time and capture cross section profiles in Al/SiO2/p-Si (MIS) Schottky diodes

The energy distribution profile of the interface states (N_ss) and their relaxation time (τ) and capture cross section (σ_p) of metal-insulator-semiconductor (Al/SiO₂/p-Si) Schottky diodes have been investigated by using the high-low frequency capacitance and conductance methods. The capacitance-voltage (C-V) and conductance-voltage (G/ω-V) characteristics of these devices were investigated by considering series resistance (R_s) effects in a wide frequency range (5 kHz-1 MHz.). It is shown that the capacitance of the Al/SiO₂/p-Si Schottky diode decreases with increasing frequency. The increase in capacitance especially at low frequencies results form the presence of interface states at Si/SiO₂ interface. The energy distributions of the interface states and their relaxation time have been determined in the energy range of (0.362-E_v)-(0.512-E_v) eV by taking into account the surface potential as a function of applied bias obtained from the measurable C-V curve (500 Hz) at the lowest frequency. The values of the interface state density (N_ss) ranges from 2.34 × 10¹² to 2.91 ×  10¹² eV⁻¹/cm², and the relaxation time (τ) ranges from 1.05 × 10⁻⁶ to 1.58 × 10⁻⁴ s, showing an exponential rise with bias from the top of the valance band towards the mid-gap.     

Temperature dependent electrical and dielectric properties of a metal/Dy2O3/n-GaAs (MOS) structure

This paper describes the structural properties, electrical and dielectric characteristics of thin Dy₂O₃ layer deposited on the n-GaAs substrate by electron beam deposition under ultra vacuum. Structural and morphological characterizations are investigated by atomic force microscopy (AFM) and X-ray diffraction measurements (XRD). The XRD shows that the elaborated Dy₂O₃ oxide has a cubic structure. The electrical and dielectric properties of Co/Au/Dy₂O₃/n-GaAs structure were studied in the temperature range of 80–500 K. The conductance and capacitance measurements were performed as a function of bias voltage and frequency. The dielectric constant (ε′), dielectric loss (ε″) and dielectric loss tangent (tanδ) of the structure are obtained from capacitance–voltage (C–V) and conductance–voltage (G/ω–V) measurements. These parameters are found to be strong functions of temperature and bias voltage. A strong negative capacitance (NC) phenomenon has been observed in C–V; hence ε′–V plots for each temperature value take negative values. The following behavior of the C and ε′ in the forward bias region has been explained with the minority-carrier injection and relaxation theory. From DC conductance study, electronic conduction is found to be dominated by thermally activated hopping at high temperature. Activation energy is deduced from the variation of conductance with temperature. The interface state density (N_ss) of the structure is of the order 1.13×10¹³ eV⁻¹ cm⁻².     

On the profile of frequency and voltage dependent interface states and series resistance in (Ni/Au)/Al0.22Ga0.78N/AlN/GaN heterostructures by using current-voltage (I-V) and admittance spectroscopy methods

In order to explain the experimental effect of interface states (N_ss) and series resistance (R_s) of device on the non-ideal electrical characteristics, current-voltage (I-V), capacitance-voltage (C-V) and conductance-voltage (G/ω-V) characteristics of (Ni/Au)/Al_0.22Ga_0.78N/AlN/GaN heterostructures were investigated at room temperature. Admittance measurements (C-V and G/ω-V) were carried out in frequency and bias voltage ranges of 2 kHz-2 MHz and (−5 V)-(+5 V), respectively. The voltage dependent R_s profile was determined from the I-V data. The increasing capacitance behavior with the decreasing frequency at low frequencies is a proof of the presence of interface states at metal/semiconductor (M/S) interface. At various bias voltages, the ac electrical conductivity (σ_ac) is independent from frequencies up to 100 kHz, and above this frequency value it increases with the increasing frequency for each bias voltage. In addition, the high-frequency capacitance (C_m) and conductance (G_m/ω) values measured under forward and reverse bias were corrected to minimize the effects of series resistance. The results indicate that the interfacial polarization can more easily occur at low frequencies. The distribution of N_ss and R_s is confirmed to have significant effect on non-ideal I-V, C-V and G/ω-V characteristics of (Ni/Au)/Al_0.22Ga_0.78N/AlN/GaN heterostructures.