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In this study, Cu(In1-xGax)(Se0.98Te0.02)2 thin film solar cells with x values of 0.17, 0.20, 0.23, and 0.26 were successfully produced by three-stage co-evaporation technique at low temperatures. The diode characteristics and solar cell parameters of thin film chalcopyrite solar cells with the structure of SLG/Mo/Cu(In1-xGax)(Se0.98Te0.02)2/CdS/ZnO/ITO/Ni-Al-Ni were investigated by current-voltage measurements. The ideality factor, series resistance, and barrier height were obtained by the Cheung-Cheung method using the current-voltage results measured in the dark at room temperature. Open-circuit voltage, short-circuit current density, fill factor, and the power conversion efficiency of the thin film solar cells were derived from the current-voltage measurements realized by a four-point measurement setup under AM1.5G standards at room temperature. It was found that the increase in the gallium content first decreased the ideality factor, however, it increased again after exceeding the x value of 0.23. While the amount of gallium was increasing, fluctuations were observed in the series resistance values. The barrier height first increased with the increasing amount of gallium and decreased after exceeding the x value of 0.23. The solar cell parameters increased by increasing the x value up to 0.23 and decreased after exceeding this point. It was found that the diode parameters have an effect on each other but the most effective diode parameter was the ideality factor. The efficiency of the Cu(In1-xGax)(Se0.98Te0.02)2 thin film solar cells was increased from 3.7% to 6.3% by increasing the x value from 0.17 to 0.23.

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The ternary copper chalcogenides CuSbS 2 (CAS) is found to have appealing optical and photovoltaic properties to be used as absorber layer in thin film solar cells. However, the difficulty to grow good quality CuSbS 2 layer of micrometer thickness by chemical bath deposition method holds a big challenge. In this work, we reported the effect of incorporating Sb 2 S 3 sacrificial layer of different thickness on structural, optical and electrical properties of CAS films. The X-ray diffraction results and Raman spectroscopic analysis confirm the formation of single-phase orthorhombic crystal structure for CuSbS 2. The increase of Sb content in CAS films with the increase in deposition time of Sb 2 S 3 layer has been reflected in the change in relative intensity ratio of characteristic Raman peaks as well as in diffraction peak profiles. The magnitude of defect states in terms of Urbach energy is decreased drastically by increasing Sb percentage in the films. A clear improvement in electrical properties of CAS films is observed with the decrease in Cu/Sb ratio. The carrier density is increased by one order of magnitude from 1016 to 1017 cm−3 and hole mobility increases from 1.14 to 4.87 cm2/Vs. The impact of Sb concentration on Scottky diode parameters of CAS/CdS heterojunction was studied by using thermionic emission model. Both the ideality factor and series resistance are decreased with the increase in Sb content. The J-V measurements reveal that the integration of Sb 2 S 3 sacrificial layer improves the PV parameters such as fill factor, open circuit voltage, photocurrent and efficiency. The overall improvement in diode parameters can be ascribed to decrease in defect states, better film quality, absorber layer thickness and improved stoichiometry of CAS films. [Display omitted] • CuSbS 2 films with different Cu/Sb ratio were developed by chemical bath deposition. • The effect of Sb 3 S 3 film thickness was studied on structural and stoichiometric properties of CuSbS 2. • The FTO/TiO 2 /CdS/CuSbS 2 /graphite heterostructure was fabricated. • The effect of Sb concentration on Scottky diode parameters of CuSbS 2 /CdS heterojunction was studied. • Sb 2 S 3 layer reduces the diode series resistance, ideality factor and enhances the efficiency. [ABSTRACT FROM AUTHOR]

We report on an n-ZnO/p-GaN heterojunction diode fabricated from zinc oxide (ZnO) films at various growth temperatures (450, 500, 550, and 600 °C) by RF sputtering. The films were subsequently annealed at 700 °C in N 2 ambient. To investigate the influence of the growth temperature of n-ZnO films, the microstructural, optical, and electrical properties were measured using scanning electron microscopy (SEM), X-ray diffraction (XRD), photoluminescence (PL), and Hall measurements. The XRD pattern showed the preferred orientation along the c -axis (002) regardless of growth temperature. The PL spectra showed a dominant sharp near-band-edge (NBE) emission. Current–voltage ( I – V ) curves showed excellent rectification behavior. The turn-on voltage of the diode was observed to be 3.2 V for the films produced at 500 °C. The ideality factor of ZnO film was observed to be 1.37, which showed the best performance of the diode. [ABSTRACT FROM AUTHOR]

A calibration method is proposed for a range finder with a six-port phase frequency discriminator. Calibration equations are derived that include phase errors resulting from both the imperfections in a six-port network and the different diode characteristics. The equations allow a simple and accurate calibration of the range finder with the six-port network. Calibration parameters are calculated from dc outputs, which are measured as the output frequency is varied. The maximum error of a distance measurement from 0.5 to 3 m is ~ 2%. [ABSTRACT FROM PUBLISHER]

• Preparation of heterostructures of solution processed MoS 2 :ReS 2 nanocrystals. • Type II band alignment between MoS 2 :ReS 2. • AFM imaging, Raman spectroscopy, XPS measurements, SEM/EDX analysis. • Interlayer coupling, charge transfer, sulfur vacancy suggested for heterostructure. • Diode characteristics with rectification ratio 25. Heterostructures of MoS 2 and ReS 2 nanocrystals were prepared in the solution phase by synthesizing the nanocomposite of these two transition metal dichalocogenides (TMDs). The heterostructure of the bulk nanocrystals of these two TMDs is shown to be forming type II heterojunction, favouring n - n junction like characteristics, exhibiting donor-acceptor like behavior. Raman spectroscopy, XPS, UV–Vis absorption measurements and EDX analysis revealed interlayer coupling, charge transfer interaction between the two TMDs and creation of sulfur vacancies in the nanocomposites. Presence of sulfur vacancies is suggested to further reduce the electron injection barrier at the ITO/MoS 2 interface, favouring flow of larger current in the forward bias direction. This conclusion was supported by the electrical characteristics of the drop cast films of the nanocomposite revealing diode characteristics with the rectification ratio of about 25. The ideality factor estimated was slightly higher which could be due to defect and trap states at the interface between the two TMDs. The study shows that by simple solution phase route of the bulk like nanocrystals, diode behavior can be obtained that can be useful for bulk heterojunction solar cell applications. [ABSTRACT FROM AUTHOR]