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Structural, optical, and electrical properties ZnTe thin films grown by magnetron sputtering technique were studied by X-ray diffraction, atomic force microscopy, Raman spectroscopy, and electrical conductivity measurements. Structural analyses showed that ZnTe thin films grown on soda–lime glass substrates have a cubic crystalline structure. This crystalline nature of the films was also discussed in terms of Raman active modes. From atomic force microscopy images, the smooth and dense surface profile was observed. The conductivity of the film at room temperature was measured as 2.45 × 10−4 (Ω cm)−1 and the temperature dependency of conductivity showed Arrhenius behavior. The dark conductivity profile was modeled by thermionic emission mechanism and activation energies were extracted. In addition, the conductivity values indicated an increasing behavior with illumination intensity applied between 20 and 115 mW/cm2. The heterojunction diode was generated by sputtering ZnTe film on n-Si wafer substrate and the rectification behavior was evaluated to determine the main diode parameters. [ABSTRACT FROM AUTHOR]

This study reveals the electrical properties of In/HfO2/n-Si structure with atomic layer-deposited interfacial oxide layer, HfO2 thin film between In top metal contact and monocrystalline Si wafer substrate. From the dark current−voltage measurements, the diode structure showed good rectifying behavior and low saturation current of about two order of magnitude and 1.2 × 10− 9 A, respectively. According to the conventional thermionic emission model, zero-bias barrier height and ideality factor were calculated from the forward bias current−voltage curve at room temperature under dark conditions as 0.79 eV and 4.22 eV, respectively. In order to get detailed information about density of interface states and series resistance of this structure, capacitance-voltage and conductance-voltage measurements in the frequency range of 10−1000 kHz were performed. As a result, a decreasing capacitance profile with increasing frequency was obtained. In addition, peak-like behavior in the capacitance profiles was observed and these were found to be the indication of density of states. Further analysis was performed on the evaluation of density of interface states values and these values were calculated by using two different methods: Hill-Coleman and high-low frequency capacitance. These profiles were also analyzed by eliminating the effect of series resistance values on the measured capacitance and conductance; then the values of corrected capacitance and conductance as a function of applied voltage were discussed. Based on these analyses on the capacitive characteristics of the diode, dielectric constant, dielectric loss, loss tangent, electrical conductivity, and the real and imaginary part of electric modulus were investigated for complete understanding on the diode characteristics. [ABSTRACT FROM AUTHOR]

Cu0.5Ag0.5InSe2 (CAIS) thin films were deposited on a glass substrate by sequential sputtering of Cu, Ag, and In2Se3-stacked film layers. Structural characterization showed that the deposited CAIS film satisfies nearly the stoichiometric form with uniform and homogeneous surface structure. The single-phase polycrystalline behavior without any secondary-phase formation was observed from the diffraction profile. The optical properties were investigated using temperature-dependent transmission measurements in the wavelength region of 600–1100 nm and in between 10 and 300 K. In the region of interest, the transmission spectra shifted towards the higher wavelengths as a result of an increase in the sample temperature. The analysis of the absorption data based on the transmission spectra resulted in absorption coefficient values of around 105 cm−1 and the presence of direct allowed optical transition. From the Tauc plots, CAIS samples were found to have three distinct direct optical transitions depending on the possible splitting in the valence band. The obtained room temperature uppermost band gap energy value of 1.09 eV was found in the energy limit of ternary analogues (CuInSe2 and AgInSe2), and also in a good agreement with the previous works in the literature. The dependency of the band gap energy on the temperature was analyzed using fundamental relations. In addition, the electrical characteristics of the film layer were discussed in four-contact conductivity measurements, and room temperature conductivity was observed as 0.8 Ω−1 cm−1. Additionally, two activation energy values were found in the temperature-dependent conductivity profile. As a diode application, CAIS/Si heterojunction was fabricated and the main diode parameters were extracted at dark and room temperature conditions. [ABSTRACT FROM AUTHOR]

In/Cu2ZnSnTe4/Si/Ag diode structure was fabricated by sputtering Cu2ZnSnTe4 (CZTTe) thin film layer on the Si layer with In front contact. The frequency dependent room temperature capacitance and conductance measurements were carried out to obtain detailed information of its electrical characteristics. Admittance spectra of the diode exhibited strong frequency dependence and the obtained values showed decreasing behavior with the increase in the applied frequency. The effect of interfacial film layer with series resistance values and density of interface states were investigated by taking into consideration of non-ideal electrical characteristics of the diode. The distribution profile of the interface states was extracted by Hill-Coleman and high–low frequency capacitance methods. As a function of frequency, they were in proportionality with the inverse of applied frequency. Dielectric constant and dielectric loss parameters were calculated from the maximum value of the diode capacitance at the strong accumulation region. The loss tangent showed a characteristic peak behavior at each frequency. Based on the time-dependent response of the interfacial charges to the applied ac field, the values of ac electrical conductivity and complex electric modulus were calculated and discussed as a function of frequency and bias voltage. [ABSTRACT FROM AUTHOR]

Cu2ZnSnTe4 (CZTTe) thin films with In metal contact were deposited by thermal evaporation on monocrystalline n-type Si wafers with Ag ohmic contact to investigate the device characteristics of an In/CZTTe/Si/Ag diode. The variation in electrical characteristics of the diode was analysed by carrying out current–voltage (I–V) measurements in the temperature range of 220–360 K. The forward bias I–V behaviour was modelled according to the thermionic emission (TE) theory to obtain main diode parameters. In addition, the experimental data were detailed by taking into account the presence of an interfacial layer and possible dominant current transport mechanisms were studied under analysis of ideality factor, n. Strong effects of temperature were observed on zero-bias barrier height (ΦB0) and n values due to barrier height inhomogeneity at the interface. The anomaly observed in the analysis of TE was modelled by Gaussian distribution (GD) of barrier heights with 0.844 eV mean barrier height and 0.132 V standard deviation. According to the Tung's theoretical approach, a linear correlation between ΦB0 and n cannot be satisfied, and thus the modified Richardson plot was used to determine Richardson constant (A∗) . As a result, A∗ was calculated approximately as 120.6 A cm–2 K–2 very close to the theoretical value for n-Si. In addition, the effects of series resistance (Rs) by estimating from Cheng's function and density of surface states (Nss) by taking the bias dependence of effective barrier height, were discussed. [ABSTRACT FROM AUTHOR]

This work indicates the device properties of polycrystalline p-AgGaInTe2 (AGIT) thin films deposited on bare and ITO-coated glass substrates with thermal evaporation technique. Device characteristics of n-CdS/p-AGIT heterostructure have been analyzed in terms of current–voltage (I–V) for different temperatures and capacitance–voltage (C–V) measurements for different frequencies, respectively. The series and shunt resistances were determined from the analysis of parasitic resistance for high forward and reverse bias voltages, respectively. The ideality factors were evaluated from I–V variation at each sample temperature as lying in between 2.51 and 3.25. The barrier height was around 0.79eV at room temperature. For low bias region, the variation in the diode parameters due to the sample temperature exhibited the thermionic emission with T0 anomaly, whereas space-charge-limited current analysis was also found to be pre-dominant carrier transport mechanism for this heterostructure. From C–V measurements, the obtained built-in potential and series resistances were found to be in good agreement with I–V results. [ABSTRACT FROM AUTHOR]

Temperature-dependent current-voltage I - V , and frequency dependent capacitance-voltage C - V and conductance-voltage G - V measurements were performed in order to analyze characteristics of CdZnTe/Si structure. Obtained profiles enable us to understand the different characteristics of the diode structure such as the carrier conduction mechanism and the nature of the interfacial layer. Over the temperature range between 220 and 340 K, taking consideration of the disparity in the forward-biased current, the diode parameters such as saturation current I 0 , zero-bias barrier height ( Φ B 0 ) and ideality factor n have been obtained. The barrier height increased (0.53 to 0.80 eV) while the ideality factor decreased (4.63 to 2.79) with increasing temperature from 220 to 340 K, indicating an improvement in the junction characteristics at high temperatures. Due to the inhomogeneity in barrier height, the conduction mechanism was investigated by Gaussian distribution analysis. Hence, the mean zero-bias barrier height ( Φ ¯ B 0 ) and zero-bias standard deviation ( σ 0 ) were calculated as 1.31 eV and 0.18, respectively. Moreover, for holes in p-type Si, Richardson constant was found to be 32.09 A cm−2 K−2 via modified Richardson plot. Using the capacitance-voltage C - V and conductance-voltage G - V characteristics, series resistance (R s) and density of interfacial traps (D it) have been also investigated in detail. A decreasing trend for R s and Dit profiles with increasing frequency was observed due to the impurities at the CdZnTe/Si interface and interfacial layer between the front metal contact and CdZnTe film. [ABSTRACT FROM AUTHOR]

In this work, p-(Ag–Ga–In–Te) polycrystalline thin films were deposited on soda-lime glass and n-type Si substrates by e-beam evaporation of AgGa 0.5 In 0.5 Te 2 crystalline powder and the thermal evaporation of Ag powder, sequentially in the same chamber. The carrier concentration and mobility of the Ag–Ga–In–Te (AGIT) film were determined as 5.82×10 15 cm −3 and 13.81 cm 2 /(V s) as a result of Hall Effect measurement. The optical analysis indicated that the band gap values of the samples were around 1.58 eV. The structural analysis was carried out by means of X-ray diffraction. Current–Voltage ( I–V ) measurements depending on the sample temperature were performed to investigate the device characteristics and the dominant conduction mechanism in an In/p-AGIT/n-Si/Ag structure. The series and shunt resistances were calculated by the help of parasitic resistance analysis as 5.73 and 1.57 × 10 4 Ω cm 2 , respectively at room temperature. The ideality factors and barrier heights were evaluated as a function of sample temperature. In the low bias region, the thermionic emission together with the generation–recombination mechanism was investigated as the dominant transport mechanism; however, in the high bias region, space charge limited current was analyzed as the other effective mechanism in the carrier conduction. The built-in potential of the device was also determined by the help of capacitance–voltage measurements. [ABSTRACT FROM AUTHOR]

In this paper, optical and electrical properties of thermally deposited Cu-Ga-S thin films were investigated using temperature-dependent optical transmission and electrical conductivity measurements. The analysis of the transmission spectra resulted in formation of three direct optical transitions due to the possible valence band splitting in the structure. The band gap values were calculated by means of absorption coefficient and incident photon energy was found in decreasing behavior as the temperature rises. The measured current-voltage values were used to extract the conductivity values which stand in the range of 1.73–2.62 (×104 Ω−1 cm−1) depending on the ambient temperature. These dark conductivity values were modeled by thermionic emission mechanism. The conductivity activation energies in the structures were calculated as 6.4, 14.5 and 40.7 meV according to the effects of grain boundary potentials. In addition, the films deposited on n-Si wafer showed a diode characteristic under the applied bias voltage between indium (In) front and silver (Ag) back contacts. From current-voltage measurements across the Si-based diode, about four orders of magnitude rectification was observed and the results were analyzed to determine the main diode parameters at dark and room temperature conditions. [ABSTRACT FROM AUTHOR]