Temperature dependence of electrical properties in In/Cu2ZnSnTe4/Si/Ag diodes

WOS: 000458625200001Cu2ZnSnTe4 (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 (Phi(B0)) 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 Phi(B0) 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 (R-s) by estimating from Cheng's function and density of surface states (N-ss) by taking the bias dependence of effective barrier height, were discussed

Vibrational modes in (TlGaS2)(x)-(TlGaSe2)(1-x)mixed crystals by Raman measurements: compositional dependence of the mode frequencies and line-shapes

TlGaS(2)and TlGaSe(2)ternary semiconducting compounds have been of scientific interest due to their large ultrafast optical nonlinearity characteristics. These remarkable properties make them promising semiconducting materials in photonic applications. A series of (TlGaS2)(x)-(TlGaSe2)(1-x)layered mixed crystals grown by Bridgman method were investigated from the standpoint of their Raman spectroscopy characteristics. Experimental Raman scattering study of crystals were reported in the frequency range of 80-400 cm(-1)for compositions ofx = 0, 0.25, 0.50, 0.75 and 1.0. The effects of crystal disorder on the line-width broadening of Raman-active modes were studied in detail. The asymmetry in the Raman line-shape was analyzed for two highest-frequency intralayer mode presenting two-mode behavior. It was shown that mixed crystal disorder effect is the major source for change of Raman line-shape with composition

Fabrication of CdSexTe1-x thin films by sequential growth using double sources

CdSexTe(1-x) (CST) ternary thin films were fabricated by stacking thermally evaporated CdSe and electron beam evaporated CdTe layers. The final structure was achieved in a stoichiometric form of approximately Cd:Se:Te = 50:25:25. The post-annealing processes at 300, 400, and 450 °C were applied to trigger the compound formation of CST thin films. The X-ray diffraction (XRD) profiles revealed that CdTe and CdSe have major peaks at 23.9° and 25.5° corresponds to (111) direction in cubic zinc-blend structure. Raman modes of CdTe were observed at 140 and 168 cm−1, while Raman modes of CdSe films were detected at 208 and 417 cm−1. The post-annealing process was found to be an effective method in order to combine both diffraction peaks and the vibrational modes of CdTe and CdSe, consequently to form CST ternary alloy. Transmission spectroscopy analysis revealed that CST films have direct band gap value of 1.6 eV

Optical and structural characteristics of electrodeposited Cd 1-xZnxS nanostructured thin films

© 2021 Elsevier B.V.The structural and optical characteristics of Cd1-xZnxS (CdZnS) thin films grown by the electrodeposition method were investigated in the present paper. The crystalline structure of the grown CdZnS thin film was determined as cubic wurtzite due to observed diffraction peaks associated with (111) and (220) planes. Atomic compositional ratios of the constituent elements were obtained using energy dispersive spectroscopy and doping concentration of the Zn was found as 5% (x ~ 0.05). Scanning electron microscopy image of the studied thin film indicated that grown film is nanostructured. Raman spectra of CdS and CdZnS thin films were measured and it was seen that observed longitudinal optical modes for CdZnS present a blue-shift. Temperature-dependent band gap energy characteristics of the thin films were studied performing transmission experiments in the 10–300 K temperature range. The analyses of the recorded transmittance spectra showed that direct band gap energy of the films decreases from 2.56 eV (10 K) to 2.51 eV (300 K) with the increase of temperature. The band gap energy vs. temperature dependency was studied applying well-known Varshni optical model and various optical parameters of the films were reported according to the results of the applied model

Deposition of CZTSe thin films and illumination effects on the device properties of Ag/n-Si/p-CZTSe/In heterostructure

WOS: 000401042300042Characterization of Cu2ZnSnSe4 (CZTSe) thin films deposited by thermal evaporation sequentially from the pure elemental sources and in-situ post annealing was carried out at 400 C under Se evaporation atmosphere. Another annealing process was applied in nitrogen atmosphere at 450 degrees C to get poly-crystalline monophase CZTSe film structure. XRD analysis together with Raman spectroscopy was used to determine the structural properties. Spectral optical absorption coefficient evaluated from transmission data showed the band gap value of 1.49 eV for annealed film. Electrical measurements indicated that CZTSe thin films have p-type semiconductor behavior with the carrier density and mobility values of 10(-19) cm(-3) and 0.70 cm(2)/(V.s). Illumination effects on the device properties of Ag/n-Si/p-CZTSe/In heterostructure were investigated by analyzing current-voltage(I-V) and frequency dependent capacitance-voltage(C-V) data. Under the illumination, Ag/n-Si/p-CZTSe/In heterostructure showed photodiode behavior having V-oc value of 100 mV and I-sc value of 27.5 mu A. With the illumination, series resistances (R-s), diode ideality factor (n) and barrier height (Phi(b)) decreased and shunt resistance (R-sh) increased. Capacitance value at lower frequency decreased due to the illumination effect. (C) 2017 Elsevier B.V. All rights reserved

Temperature-dependent optical characteristics of sputtered NiO thin films

In this work, nickel oxide thin films were deposited by radio frequency magnetron sputtering technique. X-ray diffraction (XRD), scanning electron microscopy and energy-dispersive X-ray analysis methods were applied to reveal the structural and morphological properties of sputtered thin films. The XRD pattern of films confirmed the presence of the cubic phase of nickel oxide with the preferential orientation of (200) direction. The surface morphology of thin films was observed as almost uniform and smooth. Optical aspects of sputtered film were studied by employing the room temperature Raman and temperature-dependent transmittance spectroscopy techniques in the range of 10-300 K. Tauc relation and derivative spectroscopy techniques were applied to obtain the band gap energy of the films. In addition, the relation between the band gap energy and the temperature was investigated in detail considering the Varshni optical model. The absolute zero band gap energy, rate of change of band gap energy, and Debye temperature were obtained as 3.57 eV, - 2.77 x 10(-4) eV/K and 393 K, respectively

Investigation of precursor sequence and post-annealing effects on the properties of Cu2SnZnSe4 thin films deposited by the elemental thermal evaporation

WOS: 000408512700002Cu2ZnSnSe4 (CZTSe) thin films were deposited onto soda lime glass substrates by thermal evaporation using the pure elemental sources. The influence of the sequential deposition order of Zn and Sn precursor layers for different evaporation cycles were investigated. In situ annealing at 400 degrees C under Se evaporation was applied to promote conversion of precursor layers to quaternary compound structure and additionally, subsequent post-annealing processes under nitrogen atmosphere at 450 degrees C was carried out to improve the crystalline behavior. The analyses concluded that the substrate temperature kept at 400 degrees C during selenization was not adequate to form homogenous CZTSe structure and as a result of post-annealing treatment, the polycrystalline quaternary CZTSe film structure was obtained. Structural analysis showed that in comparison with the initial Sn precursor layer, the growth process starting with Zn was found to be the preferable method to form better crystalline CZTSe structure. Furthermore, the stacking layer order and annealing processes showed the important effect on the stoichiometry and surface morphology of the films. The optical band gap energies were around 1.10 eV and also from Tauc plots, 1.40 eV was observed due to the admixture of secondary phases. The room temperature resistivity values and hole carrier densities were obtained around 10(-2) Omega cm and 1019 cm(-3), respectively. The mobility values of the samples were found in between 0.51 and 0.75 cm(2) V-1 s(-1)

Structural and temperature-tuned bandgap characteristics of thermally evaporated beta-In2S3 thin films

In2S3 is one of the attractive compounds taking remarkable interest in optoelectronic device applications. The present study reports the structural and optical characteristics of thermally evaporated beta-In2S3 thin films. The crystalline structure of the thin films was found as cubic taking into account the observed diffraction peaks in the X-ray diffraction pattern. The atomic compositional ratio of constituent elements was obtained as consistent with chemical formula of In2S3. Three peaks around 275, 309 and 369 cm(-1) were observed in the Raman spectrum. Temperature-tuned bandgap energy characteristics of the In2S3 thin films were revealed from the investigation of transmittance spectra obtained at various temperatures between 10 and 300 K. The analyses of the transmittance spectra indicated that direct bandgap energy of the In2S3 thin films decreases from 2.40 eV (at 10 K) to 2.37 eV (at 300 K) with the increase of measurement temperature. The bandgap energy vs. temperature relation was investigated by means of Varshni optical model. The fitting of the experimental data under the light of theoretical expression revealed the absolute zero bandgap energy, the rate of change of bandgap energy and Debye temperature

The effect of Zn concentration on the structural and optical properties of Cd1-xZnxS nanostructured thin films

The structural and optical properties of electrodeposited Cd1-xZnxS nanostructured thin films were investigated in the present paper for compositions of x = 0, 0.03, 0.06 and 0.09. X-ray diffraction patterns of the deposited thin films consisted of diffraction peaks related to cubic crystal lattice. The atomic compositional ratios were determined by performing energy dispersive spectroscopy measurements. Scanning electron microscopy images indicated that deposited thin films have nanostructured forms. Raman spectra of the Cd1-xZnxS thin films exhibited two vibrational modes associated with longitudinal optical mode and its first overtone. Transmission measurements were performed on the deposited thin films to get their band gap energies. It was seen from the analyses of absorption coefficient that band gap energy of Cd1-xZnxS thin films increases almost linearly from 2.40 to 2.51 eV as the composition was increased from x = 0 to x = 0.09

Material and Si-based diode analyses of sputtered ZnTe thin films

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 x 10(-4)(omega 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/cm(2). 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