Trapping levels in TlGaSe2 single crystals

Charge trapping centers in TlGaSe2 single crystals were investigated by the use of thermally stimulated current (TSC) technique. The measurements of TSC spectra in the temperature range from 90 K to 300 K were performed at a constant heating rate. The measurements showed that there are several trapping levels associated with the complex structure of overlapping peaks in the spectrum. The TSC spectra are dominated by two levels appeared at 204.1 K and 220.1 K. The experimental results indicate that the traps in TlGaSe2 associated with the spectra in the measuring range of temperature obey the monomolecular (first order) kinetics. Thus, the spectra are resolved into first order shaped peaks by the use of computerized best fit procedure. The trapping parameters, such as the energy depth, temperature dependent frequency factor and capture cross section together with the concentrations of the corresponding eight discrete levels, are computed. These centers all having high capture cross sections are found to be at the energies of 0.20 eV, 0.22 eV, 0.26 eV, 0.31 eV, 0.35 eV, 0.49 eV, 0.60 eV and 0.67 eV with low concentrations of 8.9 x 10(13), 7.8 x 10(13), 1.1 x 10(14), 3.5 x 10(13), 4.4 x 10(13), 3.8 x 10(13), 9.8 x 10(14) and 8.8 x 10(14) cm(-3), respectively. (C) 2013 Elsevier B. V. All rights reserved

Trapping levels in TlGaSe2 single crystals

Charge trapping centers in TlGaSe2 single crystals were investigated by the use of thermally stimulated current (TSC) technique. The measurements of TSC spectra in the temperature range from 90 K to 300 K were performed at a constant heating rate. The measurements showed that there are several trapping levels associated with the complex structure of overlapping peaks in the spectrum. The TSC spectra are dominated by two levels appeared at 204.1 K and 220.1 K. The experimental results indicate that the traps in TlGaSe2 associated with the spectra in the measuring range of temperature obey the monomolecular (first order) kinetics. Thus, the spectra are resolved into first order shaped peaks by the use of computerized best fit procedure. The trapping parameters, such as the energy depth, temperature dependent frequency factor and capture cross section together with the concentrations of the corresponding eight discrete levels, are computed. These centers all having high capture cross sections are found to be at the energies of 0.20 eV, 0.22 eV, 0.26 eV, 0.31 eV, 0.35 eV, 0.49 eV, 0.60 eV and 0.67 eV with low concentrations of 8.9 x 10(13), 7.8 x 10(13), 1.1 x 10(14), 3.5 x 10(13), 4.4 x 10(13), 3.8 x 10(13), 9.8 x 10(14) and 8.8 x 10(14) cm(-3), respectively. (C) 2013 Elsevier B. V. All rights reserved

The forward bias current density-voltage-temperature (J-V-T) characteristics of Al-SiO2-pSi (MIS) Schottky diodes

Metal-insulator-semiconductor Schottky diodes were fabricated to investigate the tunnel effect and the dominant carrier transport mechanism by using current density-voltage (J-V) and capacitance-voltage (C-V) measurements in the temperature range of 295-370 K. The slope of the ln J-V curves was almost constant value over the nearly four decades of current and the forward bias current density J is found to be proportional to Jo (T) exp(AV). The values of Nss estimated from J-V and C-V measurements decreased with increasing temperature. The temperature dependence of the barrier heights obtained from forward bias J-V was found to be entirely different than that from the reverse bias C-V characteristics. All these behaviours confirmed that the prepared samples have a tunnel effect and the current transport mechanism in the temperature range of 295-370 K was predominated by a trap-assisted multi-step tunnelling, although the Si wafer has low doping concentration and the measurements were made at moderate temperature

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

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 N ss 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 CHF - CLF method. The obtained value of Nss is about 1014 eV-1 cm-2 order and these values are suitable for an electronic device. © World Scientific Publishing Company

The fabrication of Al/p-Si (MS) type photodiode with (%2 ZnO-doped CuO) interfacial layer by sol gel method and their electrical characteristics

© 2019 Elsevier B.V. In this study, Al/p-Si (MS) type photodiodes with (%2 ZnO-doped CuO) interlayer were fabricated to investigate the effects of this interlayer on the electrical characteristics. Besides, the structural properties of this interlayer were also investigated using AFM. The forward and reverse bias current voltage (I-V) measurements were carried out both in dark and various illumination intensities (10–100 mW cm −2 ) whereas the capacitance/conductance-voltage (C/G-V) measurements were carried out at various frequencies (10 kHz-1 MHz) in dark at room temperature. Experimental results show that the values of current increase with increasing illumination intensity especially in the reverse bias region due to high electric field. Furthermore, the observed good response to the illumination indicated that the fabricated structures can be used as a photo-detector/diode in the electric and optic applications. The slope (m) was obtained from the log(I PH )-log(P) plot as 0.821 which is lower than unity which suggested that the photoconduction mechanism exhibited a linear behavior. The observed increase in the C and G values with decreasing frequency was attributed to the existence of surface states (N ss ) which are located between interlayer and semiconductor and their relaxation times. The obtained frequency dependent R s values show that it is more effective both on the C-V and G/w-V characteristics especially at accumulation region at high frequencies

Frequency and voltage dependence of electrical and dielectric properties in metal-interfacial layer-semiconductor (MIS) type structures

© 2020 Elsevier B.V.Zinc-ferrite nanostructures were fabricated using ultrasonic-assisted-method. FE-SEM, EDX and XRD were utilized for the investigation of morphological and structural properties. Au/(ZnFe2O4-PVP)/n-Si MPS structures were prepared for the purpose of characterizing electrical and dielectric properties via impedance-spectroscopy-method (ISM) between -2 V and 5 V in the frequency range of 10 kHz-5MHz. The frequency-dependent values of electrical parameters such as VD, ND, EF, WD and ΦC-V were extracted from the reverse bias C−2-V. Voltage-dependent profiles of Rs and Nss was calculated using Nicollian-Brews and high-low frequency capacitance (CLF-CHF) methods. Results showed Nss is more effective are depletion and inversion whereas accumulation region is the region at which Rs is more effective. The real and imaginary parts of ε* and M* were calculated and showed strong dependence on frequency and voltage. The higher values of C, G/ω or ϵ', ϵ" at low frequencies and observed peak in the M″-V and (tanδ)-V were associated with Nss

The Structural and Electrical Properties of the Au/n-Si (MS) Diodes with Nanocomposites Interlayer (Ag-Doped ZnO/PVP) by Using the Simple Ultrasound-Assisted Method

© 1963-2012 IEEE.In this paper, Au/Ag-doped ZnO/polyvinyl pyrrolidone (PVP)/n-Si [metal-polymer-semiconductor (MPS)] Schottky Barrier Diodes (SBDs) were fabricated. The structural properties of the Ag-doped ZnO/PVP nanocomposites have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analyses. The XRD pattern indicated that the samples have high purity ZnO and Ag materials and have not observed other peaks. The mean crystallite size of nanoparticles was calculated using Debye-Scherer's equation and the measured sizes reveal clearly the formation of small nanocrystals. The SEM and EDX results show the sheetlike ZnO nanostructures and also confirm the presence of Zn, O, and Ag materials with the nonstoichiometric ratio. The values of ideality factor (n), zero-bias barrier height (ΦB0), and series resistance (RS) of the MPS-type SBD were obtained from both the thermionic emission (TE) and Cheung function and the observed some discrepancy between them was due to the voltage-dependent of these parameters and the nature of the calculation method. The value of surface states (Nss) was changed from 2.2 × 1013 eV-1 cm-2 at (Ec ? 0.44) eV to 8.19 × 1012 eV-1 cm-2 at (Ec ? 0.69) eV and these values are more suitable for the MPS-type SBD. The values of doping-donor atoms (ND), depletion layer width (WD), and φB [capacitancevoltage (C?V )] were obtained from the reverse bias C-2?V plot as a function of frequency. While the value of ND decreases with increasing frequency,WD increases almost as exponentially. However, there is a good relationship between φB (C?V ) and ln(f )

A comparison of electrical parameters of Au/n-Si and Au/(CoSO 4 –PVP)/n-Si structures (SBDs) to determine the effect of (CoSO 4 –PVP) organic interlayer at room temperature

© 2019, Springer Science+Business Media, LLC, part of Springer Nature. In this study, the Au/n-Si structures with and without (CoSO 4 –PVP) organic interlayer were fabricated on the same n-Si wafer and electrical characteristics of them were analyzed by using current, capacitance, and conductance measurements in forward and reverse bias voltages and experimental results were compared with each other. The values of ideality factory (n), zero-bias barrier height (Φ Bo ), and the rectifying ratio (RR at ± 3 V) for Au/n-Si and Au/(CoSO 4 –PVP)/n-Si structures were found as 2.453, 0.732 eV, 2.01 × 10 3 and 2.489, 0.799, 5.37 × 10 4 by using the I–V measurements, respectively. The RR of Au/(CoSO 4 –PVP)/n-Si structures at ± 3 V was 26.77 times higher than Au/n-Si structure. The concentration of donor-atoms (N D ), Fermi energy (E F ) and barrier height for these two structures were found as 15.06 × 10 14 cm −3 , 0.254 eV, 0.744 eV and 2.310 × 10 14 cm −3 , 0.303 eV, 1.010 eV from the C −2 –V characteristics in the reverse bias region at 1 MHz in dark, respectively. These results show that the use of (CoSO 4 –PVP) polymer interface layer at Au/n-Si interface improves the performance of these structures. Additionally, a simple ultrasound-assisted method has been utilized to grown cobalt sulfide nanostructures. The morphological and structural analyses of them have been investigated by scanning electron-microscopy, and X-ray diffraction methods

Investigation of dielectric relaxation and ac conductivity in Au/(carbon nanosheet-PVP composite)/n-Si capacitors using impedance measurements

The frequency and voltage dependence of complex dielectric constant (ϵ∗) , electric modulus (M∗) , tangent loss (tan δ) , ac electrical conductivity (σac) , and impedance (Z∗) of the Au/(Carbon Nanosheet-PVP composite)/n-Si capacitors was investigated using the impedance spectroscopy (IS) method in wide frequency range (1 kHz–5 MHz). ϵ′- V plot yielded two distinct peaks located at 1.0 and 2.5 V in the low-frequency region. As the value of M′ increases with increasing frequency, M′ ′ shows a peak whose position shifts toward positive voltages with increasing frequency. Such response of these parameters to frequency can be attributed to the interfacial polarization and a special distribution of interface states at Au/interlayer interface since the dipoles and interface states both have enough time to follow the ac signal easily, thus the dipoles rotate around themselves and align with the field. The plot of ln (σac) - ln (ω) has three linear regions corresponding to low, intermediate, and high frequencies, each yielding a different slope value thus indicating a different conduction mechanism for each frequency range. It was found that the obtained value of ϵ′ is approximately five times higher than the bulk SiO2 at 1 kHz. The dielectric characterization reveals that the presence of the (Carbon Nanosheet-PVP composite) interlayer affects the electrophysical features of the fabricated device. In other words, the utilization of the abovementioned interlayer is showing a considerable improvement in the performance of the MS structure with respect to high-energy storage capacity. The use of the Carbon Nanosheet-PVP composite as an interfacial layer instead of conventional insulators has improved device performance over a wide range of frequencies and voltages