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

2014 ◽  
Vol 28 (23) ◽  
pp. 1450153 ◽  
Author(s):  
İ. Yücedağ ◽  
A. Kaya ◽  
Ş. Altındal
Keyword(s):  
Dielectric Constant ◽  
Electric Modulus ◽  
Forward Bias ◽  
Surface States ◽  
Ac Electrical Conductivity ◽  
Low Frequencies ◽  
Voltage Range ◽  
The Real ◽  
Anomalous Peak ◽  
Co Doped

The dielectric properties, electric modulus and ac electrical conductivity (σac) of Al / Co -doped (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 capacitance-voltage (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″.

Investigation of Dielectric Properties, Electric Modulus and Conductivity of the Au/Zn-Doped PVA/n-4H-SiC (MPS) Structure Using Impedance Spectroscopy Method

2020 ◽  
Vol 234 (3) ◽  
pp. 505-516 ◽  
Author(s):  
Havva Elif Lapa ◽  
Ali Kökce ◽  
Ahmet Faruk Özdemir ◽  
Şemsettin Altındal
Keyword(s):  
Impedance Spectroscopy ◽  
Electric Modulus ◽  
Forward Bias ◽  
Spectroscopy Method ◽  
Complex Dielectric Constant ◽  
Relaxation Processes ◽  
Low Frequencies ◽  
High Frequencies ◽  
The Real ◽  
Wide Range

AbstractThe 50 nm thickness Zn-doped polyvinyl alcohol (PVA) was deposited on n-4H-SiC semiconductor as interlayer by electro-spinning method and so Au/Zn-doped PVA/n-4H-SiC metal-polymer-semiconductor (MPS) structure were fabricated. The real and imaginary parts of the complex dielectric constant (ε′, ε′′), loss-tangent (tan δ), the real and imaginary parts of the complex electric modulus (M′, M′′) and ac electrical conductivity (σac) behavior of this structure were examined using impedance spectroscopy method in a wide range of frequency (1 kHz–400 kHz) and voltage (−1 V)–(+6 V) at room temperature. The values of ε′, ε′′, tan δ, M′, M′′ and σac are determined sensitive to the frequency and voltage in depletion and accumulation regions. The values of ε′ and ε′′ decrease with increasing frequency while the values of M′ and σac increase. The peak behavior in the tan δ and M′′ vs. frequency curves was attributed to the dielectric relaxation processes and surface states (Nss). The plots of ln (σac) vs. ln (f) at enough high forward bias voltage (+6 V) have three linear regions with different slopes which correspond to low, intermediate and high frequencies, respectively. The dc conductivity is effective at low frequencies whereas the ac conductivity effective at high frequencies. According to experimental results, the surface/dipole polarizations can occur more easily occur at low frequencies and the majority of Nss between Zn-doped PVA and n-4H-SiC contributes to the deviation of dielectric behavior of this structure.

A SYSTEMATIC STUDY ON THE DIELECTRIC RELAXATION, ELECTRIC MODULUS AND ELECTRICAL CONDUCTIVITY OF Al/Cu:TiO2∕n-Si (MOS) STRUCTURES/CAPACITORS

2020 ◽  
Vol 27 (10) ◽  
pp. 1950217
Author(s):  
M. YILDIRIM ◽  
A. KOCYIGIT
Keyword(s):  
Electrical Conductivity ◽  
Electric Modulus ◽  
Forward Bias ◽  
Industrial Applications ◽  
Dielectric Parameters ◽  
Mos Capacitors ◽  
Cu Doping ◽  
The Real ◽  
Complex Electric Modulus ◽  
Wide Range

The various levels (5%, 10% and 15%) of Cu-doped TiO2 thin films were grown on the [Formula: see text]-type silicon (Si) wafer by spin coating technique to obtain Al/(Cu:TiO[Formula: see text]/[Formula: see text]-Si (MOS) capacitors. Both the real and imaginary components of complex dielectric ([Formula: see text], complex electric modulus ([Formula: see text], loss tangent (tan [Formula: see text] and alternating electrical conductivity ([Formula: see text] of the obtained Al/(Cu:TiO[Formula: see text]-Si (MOS) capacitors were studied by taking into account the effects of Cu-doping levels into TiO2 viaimpedance spectroscopy method (ISM) in the wide range voltage ([Formula: see text][Formula: see text]V) and frequency (10[Formula: see text]kHz–1[Formula: see text]MHz). All the obtained dielectric parameters were obtained as strongly dependent on frequency, voltage and Cu doping level. The observed anomalous peak in the forward bias region both in the real and imaginary components of [Formula: see text], tan [Formula: see text], complex electric modulus ([Formula: see text] and [Formula: see text] were attributed to the Cu:TiO2 interlay er, series resistance ([Formula: see text], surface states ([Formula: see text], interfacial/surface and dipole polarizations. The higher values of [Formula: see text] at low and intermediate frequencies implied that [Formula: see text] have enough time to follow external ac signal, and also dipoles respond to the applied field to reorient themselves. Consequently, the fabricated Al/(Cu:TiO[Formula: see text]-Si can be successfully used as MOS capacitor or MOS-field-effect transistor (MOSFET) in the industrial applications in near future.

On the anomalous peak in the forward bias capacitance and conduction mechanism in the Au/n-4H SiC (MS) Schottky diodes (SDs) in the temperature range of 140–400 K

2015 ◽  
Vol 29 (04) ◽  
pp. 1550010 ◽  
Author(s):  
Ahmet Kaya
Keyword(s):  
Series Resistance ◽  
Schottky Diodes ◽  
Forward Bias ◽  
Surface States ◽  
Negative Temperature ◽  
Anomalous Peak ◽  
Increasing Temperature ◽  
Straight Lines ◽  
Accumulation Region ◽  
Good Agreement

The temperature and voltage dependence profile of the surface states (Nss), series resistance (Rs) and electrical conductivity (σ ac ) have been investigated in temperature and voltage ranges of 140–400 K and (-5 V )-(6 V ), respectively. The value of barrier height (BH) decreases with increasing temperature as ΦB(T) = (1.02 - 4×10-4⋅ T ) eV. These values of negative temperature coefficient (-4×10-4 eV ⋅ K -1) is in good agreement with the α of band gap of SiC (-3.1×10-4 eV ⋅ K -1). Capacitance-voltage (C–V) plots for all temperatures show an anomalous peak in the accumulation region because of the effect of series resistance (Rs) and Nss. The effect of Rs and Nss on the C and conductance (G) are found noticeable high especially at low temperatures. The decrease in C values also corresponds to an increase in G/ω values in the accumulation region. In addition, Ln (σ ac ) versus q/kT plots have two straight lines with different slopes which are corresponding to below and above room temperatures for various forward biases which are an evident two valid possible conduction mechanisms. The values of activation energy (Ea) were obtained from the slope of these plots and they changed from 6.3 meV to 4.7 meV below room temperatures and 42.5 meV to 34.4 meV for above room temperatures, respectively.

Energy density distribution profiles of surface states, relaxation time and capture cross-section in Au/n-type 4H-SiC SBDs by using admittance spectroscopy method

2014 ◽  
Vol 28 (17) ◽  
pp. 1450104 ◽  
Author(s):  
A. Kaya ◽  
Ö. Sevgili ◽  
Ş. Altındal
Keyword(s):  
Relaxation Time ◽  
Energy Density ◽  
Density Distribution ◽  
Electronic Device ◽  
Surface States ◽  
Depletion Region ◽  
Low Frequencies ◽  
Energy Density Distribution ◽  
Conductance Method ◽  
Anomalous Peak

Au /n-type 4H - SiC diodes were fabricated and their electrical characteristics have been investigated by using the capacitance/conductance-voltage-frequency (C–V–f and G/w–V–f) measurements method at room temperature. The main parameters such as the doping atoms (ND), diffusion potential (VD) and barrier height (ΦB(C–V)) values were obtained from the reverse bias C-2–V plots for each frequency. C and G/ω values decrease with increasing frequency as almost exponential for each voltage and these changes in C and G/ω are considerably high at low frequencies due to the contribution of surface states (Nss) to the measured C and G/ω. The resistivity (Ri) versus V plots were also obtained by using the C and G data and they exhibit an anomalous peak which is corresponding to the depletion region at each frequencies and its magnitude decreases with increasing frequency. The energy density distribution of Nss and their relaxation time (τ) were obtained from the conductance method and they range from 1.53 × 1014 eV-1 cm-2 to 1.03 × 1014 eV-1 cm-2 and 1.29 × 10-4 s to 3.35 × 10-5 s, respectively, in the energy range of (0.585-Ev) – (0.899-Ev) eV. The voltage dependent of Nss was also obtained from C HF – C LF method. The obtained value of Nss is about 1014 eV-1 cm-2 order and these values are suitable for an electronic device.

Tuning the mechanical and dielectric properties of zinc incorporated hydroxyapatite

2020 ◽  
Vol 16 ◽  
Author(s):  
Alliya Qamar ◽  
Rehana Zia ◽  
Madeeha Riaz
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Bone Growth ◽  
Healing Process ◽  
Secondary Phase ◽  
Chemical Precipitation ◽  
Hexagonal Structure ◽  
Precipitation Method ◽  
Low Frequencies ◽  
A Minor

Background: Hydroxyapatite is similar to bone mineral in chemical composition, has good biocompatibility with host tissue and bone. Objective: This work aims to tailor the mechanical and dielectric properties of hydroxyapatite with zinc sudstitution, to improve wearability of implant and accelerate the healing process. Method: Pure and zinc incorporated hydroxyapatite Ca10(PO4)6(OH)2 samples have been successfully prepared by means of the chemical precipitation method. Results: The results showed that hydroxyapatite(Hap) having hexagonal structure was the major phase identified in all the samples. It was found that secondary phase of β-tricalcium phosphate (β-TCP) formed due to addition of Zinc resulting in biphasic structure BCP (Hap + β-TCP). A minor phase of ZnO also formed for higher concentration of Zn (Zn ≥ 2mol%) doping. It was found that the Zn incorporation to Hap enhanced both mechanical and dielectric properties without altering the bioactive properties. The microhardness increased upto 0.87 GPa for Zn concentration equal to 1.5mol%, which is comparable to the human bone ~0.3 - 0.9 GPa. The dielectric properties evaluated in the study showed that 1.5 mol% Zn doped hydroxyapatite had highest dielectric constant. Higher values of dielectric constant at low frequencies signifies its importance in healing processes and bone growth due to polarization of the material under the influence of electric field. Conclusion: Sample Z1.5 having 1.5 mol% Zn doping showed the most optimized properties suitable for bone regeneration applications.

ON THE DIELECTRIC BEHAVIOR OF LiCo3/5Fe2/5VO4 CERAMICS

2010 ◽  
Vol 24 (07) ◽  
pp. 665-670
Author(s):  
MOTI RAM
Keyword(s):  
Activation Energy ◽  
Dielectric Constant ◽  
Frequency Dependence ◽  
Chemical Method ◽  
Arrhenius Plot ◽  
Dielectric Behavior ◽  
Tangent Loss ◽  
Low Frequencies ◽  
Different Temperatures ◽  
Tan Δ

The LiCo 3/5 Fe 2/5 VO 4 ceramics has been fabricated by solution-based chemical method. Frequency dependence of the dielectric constant (εr) at different temperatures exhibits a dispersive behavior at low frequencies. Temperature dependence of εr at different frequencies indicates the dielectric anomalies in εr at Tc (transition temperature) = 190°C, 223°C, 263°C and 283°C with (εr) max ~ 5370, 1976, 690 and 429 for 1, 10, 50 and 100 kHz, respectively. Frequency dependence of tangent loss ( tan δ) at different temperatures indicates the presence of dielectric relaxation in the material. The value of activation energy estimated from the Arrhenius plot of log (τd) with 103/T is ~(0.396 ± 0.012) eV.

Temperature Sensors Based on AlN/4H-SiC Diodes

2021 ◽  
Vol 13 (7) ◽  
pp. 1318-1323
Author(s):  
Myeong-Cheol Shin ◽  
Dong-Hyeon Kim ◽  
Seong-Woo Jung ◽  
Michael A. Schweitz ◽  
Sang-Mo Koo
Keyword(s):  
Annealing Temperature ◽  
Schottky Diodes ◽  
Forward Bias ◽  
Temperature Sensors ◽  
Electrical Characteristics ◽  
Voltage Range ◽  
Radio Frequency Sputtering ◽  
Sensing Applications ◽  
Current Voltage ◽  
Dc Bias

ABSTRACTThis study report on the formation of AlN/SiC heterostructure Schottky diodes for use of temperature sensing applications enhance the sensitivity. We analyzed the sensitivity of the AlN/SiC Schottky diode sensor depending on the annealing temperature. AlN/4H-SiC Schottky diodes were fabricated by depositing aluminum nitride (AlN) thin film on 4H/SiC by radio frequency sputtering. The forward bias electrical characteristics were determined under DC bias (in the voltage range of 0–1.5 V). The ideality factor, barrier height, and sensitivity were derived through current–voltage–temperature (I–V–T) measurements in the temperature range of 300–500 K. The sensitivity of the AlN/4H-SiC Schottky barrier diode ranged from 2.5–5.0 mV/K.

Effect of Ce-Mn Codoping on the Structural, Morphological and Electrical Properties of the BaTiO3 Based Ceramics

2021 ◽  
Vol 11 (4) ◽  
pp. 12215-12226
Keyword(s):  
Dielectric Constant ◽  
Electrical Properties ◽  
Doping Concentration ◽  
Xrd Analysis ◽  
Solid State Reaction Method ◽  
Lattice Parameter ◽  
Stoichiometric Ratio ◽  
Co Doping ◽  
Mn Doped ◽  
Co Doped

Undoped, Cerium (Ce) doped, Manganese (Mn) doped and Ce-Mn co-doped Barium Titanate (BaTiO3) with the general formula Ba1-xCexMnyTi1-yO3 (where x = 0.00, 0.01, 0.02, 0.03, y = 0.00; x = 0.00, y =0.01, 0.02, 0.03; and x = y = 0.01, 0.02,0.03) were synthesized by solid-state reaction method and sintered at 1200 C for 4 hr with an aim to study their structural and electrical properties. The grain size of the samples has been estimated using the Scanning Electron Microscopy (SEM). The X-ray Diffraction (XRD) analysis indicates that the structure of the Ce-doped and Ce-Mn co-doped BaTiO3 is cubic. However, the undoped BaTiO3 and Mn-doped BaTiO3 confirmed the tetragonal-cubic mixed phases. With the change of doping concentrations, the positions of different peaks shifted slightly. The lattice parameter varied irregularly with increasing doping concentration because of Mn's changeable valency. EDX spectra confirmed the presence of Ba, Ti, Ce, and Mn contents in the co-doped samples with stoichiometric ratio. Crystallinity is observed to be clearly increased when Ce-Mn is co-doped in BaTiO3. J-V characteristic curves indicate transition from conducting to semiconducting nature for the doped and co-doped samples with the increase in temperature. The dielectric constant of the samples increases up to 4500 with the doping concentration. The higher values of dielectric constant are observed for the 2% Mn-doped and 1% Ce-Mn co-doped samples compared to the other undoped samples. For the undoped and Mn-doped samples, constant dielectric values increase with temperature but decrease for the Ce-doped and Ce-Mn co-doped samples. It is inferred that co-doping of BaTiO3 with Ce and Mn would be beneficial and economical for its applications.

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