Search

Thin film solar cells are an exciting topic for low cost and high efficient solar cells. Owing to the high price of the indium metal in the fabrication of copper indium gallium diselenide (CIGS) solar cells, Cu2ZnSn(SSe)(4) thin films are used as a new material to reduce the cost and increase the efficiency. As an alternative absorber material for solar cell production, Cu2ZnTi(S:Se)(4) thin films were deposited by the co-sputtering method at various temperatures. During the deposition, Cu, ZnSe and Ti targets were used as metal sources. The Cu2ZnTi(S:Se)(4) thin films were annealed in H2S:Ar (1:9) atmosphere. The morphological, structural and optical properties of Cu2ZnTi(S:Se)(4) thin films was analyzed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) Raman spectroscopy and UV-Vis-NIR spectrometer. It was seen that the thin films had good optical absorption till the infrared region and the band gap of the Cu2ZnTi(S:Se)(4) thin films were smaller than the conventional Cu2ZnSnS4 thin films. Furthermore, fabrication of a solar cell with 1.96% power conversion efficiency was reported using a Cu2ZnTi(S:Se)(4) thin film as a low cost absorber layer. (c) 2019 Elsevier Ltd. All rights reserved.

Metal oxide nanostructures are highly attractive for the fabrication of gas sensors due to their high surface‐to‐volume ratios. The design of novel structures has great importance to improve sensing behavior. Atomic layer deposited ZnO thin film on vertically aligned silicon nanowire (Si NW) arrays were used to understand the influence of etching time on CO2 sensing behavior of the SiNW/ZnO structure. The metal-assisted chemical etching method was used to realize SiNW arrays. The etching processes were performed for 5, 10, 30, and 60 min. The linear relationship between etching time and Si NW length was reported. 30 nm ZnO thin films were deposited on Si NWs by atomic layer deposition (ALD) method using diethyl Zinc and H2O as Zn and O2 sources, respectively. The CO2 sensing properties of the SiNW/ZnO structures were examined at ambient temperature and low CO2 concentration. The testing measurement results reveal that the sensor realized on un-etched Si does not exhibit any sensitivity. While the SiNW/ZnO was sensitive to CO2, the sensor sensitivity increase with the etching time due to the increase in the specific reactive surface. Moreover, the realized sensors have a relatively low response and recovery times, in the range of 2–7 s, by comparison to the reported ones in the literature.

MoS2 is one of the most promising materials due to its exciting properties. Al/MoS2/n–Si heterojunction diode was acquired via the formation of a MoS2 thin film on n–Si semiconductor using radio frequency (RF) sputtering technique and an evaporation of Al metal on MoS2/n–Si structure. The morphological and optical properties of the RF sputtered MoS2 thin film were examined using atomic force microscopy (AFM), scanning electron microscopy (SEM) and UV–vis data. The electrical parameters of Al/MoS2/n-Si heterojunction on temperature were investigated using its current-voltage (I–V) measurements within 150–400 K in the dark. The results showed that while the ideality factor and series resistance values of the junction decreased, the barrier height values increased with the increase in temperature. The linear correlation between ideality factor and barrier height values was also reported for Al/MoS2/n–Si heterojunction.

Cu2ZnTiS4 thin films have been deposited on glass by the reactive cosputtering technique with high-purity ZnS and Cu and Ti metals as targets and H2S as reactive gas. Cu2ZnTiS4 thin films were obtained at various temperatures and H2S flows and were annealed in H2S atmosphere. The structural, morphological, and optical properties of the Cu2ZnTiS4 thin films were examined by scanning electron microscopy, energy-dispersive spectroscopy, x-ray diffraction (XRD) analysis, and ultraviolet-visible (UV-Vis) spectroscopy. Agglomeration was found to increase with increasing temperature. The XRD peaks of the Cu2ZnTiS4 thin films were consistent with those of Cu2ZnSnS4. Furthermore, the optical bandgaps of the Cu2ZnTiS4 films were lower than those of conventional Cu2ZnSnS4 thin films.

Cadmium sulfide (CdS) thin films were deposited onto soda lime glasses and p-Si semiconductors at various substrate temperatures (40, 150 and 275 °C) by radio frequency (RF) sputtering technique. The effect of substrate temperature on morphological, structural and optical properties of CdS thin films were analyzed by means of atomic force microscopy (AFM), x-ray diffraction (XRD) and uv–vis spectrum data. The results showed that the average roughness (Ra) of thin films increased from 2.0 to 4.0 nm and all films had hexagonal wurtzite structure. The optical band gaps of CdS thin films varied between 2.46–2.43 eV. Characteristic parameters of CdS/p-Si heterojunctions including ideality factor, barrier height, series resistance and rectification ratio were measured. It was seen that both ideality factor and barrier height values of the heterojunctions increase with the increase substrate temperature. It was attributed to increase in inhomogenity of the thin films. Furthermore, the photoelectrical parameters of CdS/p-Si heterojunctions were studied.

Cu2ZnSnS4 (CZTS) is low cost and constitutes non-toxic materials abundant in the earth crust. Environment friendly solar cell absorber layers were fabricated by a thermal co-evaporation technique. Elemental composition of the film was stated by energy dispersive spectroscopy (EDS). Some optical and electrical properties such as absorption of light, absorption coefficient, optical band gap charge carrier density, sheet resistance and mobility were extracted. Optical band gap was found to be as 1.44 eV, besides, charge carrier density, resistivity and mobility were found as 2.14×1019 cm−3, 8.41×10−4 Ω cm and 3.45×102 cm2 V−1 s−1, respectively. In this study Ag/CZTS/n-Si Schottky diode was fabricated and basic diode parameters including barrier height, ideality factor, and series resistance were concluded using current–voltage and capacitance–voltage measurements. Barrier height and ideality factor values were found from the measurements as 0.81 eV and 4.76, respectively, for Ag/CZTS/n-Si contact.

A Mo/n-type 6H-SiC/Ni Schottky barrier diode (SBD) was fabricated by sputtering Mo metal on n-type 6H-SiC semiconductor. Before the formation of Mo/n-type 6H-SiC SBD, an ohmic contact was formed by thermal evaporation of Ni on n-type 6H-SiC and annealing at 950 °C for 10 min. It was seen that the structure had excellent rectification. The electrical parameters were extracted using its current–voltage ( I – V ) and capacitance–voltage ( C – V ) measurements carried out at room temperature. Very high (1.10 eV) barrier height and 1.635 ideality factor values were reported for Mo/n-type 6H-SiC using ln I – V plot. The barrier height and series resistance values of the diode were also calculated as 1.413 eV and 69 Ω from Norde׳s functions, respectively. Furthermore, 1.938 eV barrier height value of Mo/n-type 6H-SiC SBD calculated from C – V measurements was larger than the one obtained from I – V data.

Electrical properties of Ta/n-Si and Ta/p-Si Schottky barrier diodes obtained by sputtering of tantalum (Ta) metal on semiconductors have been investigated. The characteristic parameters of these contacts like barrier height, ideality factor and series resistance have been calculated using current voltage (I-V) measurements. It has seen that the diodes have ideality factors more than unity and the sum of their barrier heights is 1.21 eV which is higher than the band gap of the silicon (1.12 eV). The results have been attributed the effects of inhomogeneities at the interface of the devices and native oxide layer. In addition, the barrier height values determined using capacitance-voltage (C-V) measurements have been compared the ones obtained from I-V measurements. It has seen that the interface states have strong effects on electrical properties of the diodes such as C-V and Rs-V measurements. © 2010 Elsevier Ltd. All rights reserved.

To see the effects of substrate temperature on Cr2O3/n-Si heterojunctions, Cr2O3 thin films were formed on n-Si and glass substrates at 40, 150 and 250 °C by radio frequency (RF) reactive sputtering technique. High purity Cr was used as target and oxygen was used as reactive gas. Optical properties of Cr2O3/n-Si thin films were analyzed using UV-vis data. The band gaps of the films were compared. The electrical properties of Cr2O3/n-Si heterojunction were tested by their current voltage (I-V) measurements in dark. It was observed that the heterojunction which was fabricated by forming Cr2O3 thin film at 250 °C gave better rectification. The characteristic electrical parameters such as barrier height, ideality factor and series resistance were calculated by using its I-V data. The influence of light intensity on photovoltaic effect behavior of the device was also calculated, finally the barrier height value of the structure obtained from capacitance-voltage (C-V) data were compared with the one calculated from I-V measurements.

Cataloged from PDF version of article. In this study, we implanted N(+) and N(2)(+) ions into sputter deposited amorphous boron carbide (a-BC) and diamond like carbon (DLC) thin films in an effort to understand the chemical bonding involved and investigate possible phase separation routes in boron carbon nitride (BCN) films. In addition, we investigated the effect of implanted C(+) ions in sputter deposited amorphous boron nitride (a-BN) films. Implanted ion energies for all ion species were set at 40 KeV. Implanted films were then analyzed using x-ray photoelectron spectroscopy (XPS). The changes in the chemical composition and bonding chemistry due to ion-implantation were examined at different depths of the films using sequential ion-beam etching and high resolution XPS analysis cycles. A comparative analysis has been made with the results from sputter deposited BCN films suggesting that implanted nitrogen and carbon atoms behaved very similar to nitrogen and carbon atoms in sputter deposited BCN films. We found that implanted nitrogen atoms would prefer bonding to carbon atoms in the films only if there is no boron atom in the vicinity or after all available boron atoms have been saturated with nitrogen. Implanted carbon atoms also preferred to either bond with available boron atoms or, more likely bonded with other implanted carbon atoms. These results were also supported by ab-initio density functional theory calculations which indicated that carbon-carbon bonds were energetically preferable to carbon-boron and carbon-nitrogen bonds. (C) 2011 American Institute of Physics.

Cataloged from PDF version of article. In this study, we have synthesized boron, carbon, and nitrogen containing films using RF sputter deposition. We investigated the effects of deposition parameters on the chemical environment of boron, carbon, and nitrogen atoms inside the films. Techniques used for this purpose were grazing incidence reflectance-Fourier-transform infrared spectroscopy (GIR-FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). GIR-FTIR experiments on the B-C-N films deposited indicated presence of multiple features in the 600 to 1700 cm(-1) range for the infrared (IR) spectra. Analysis of the IR spectra, XPS and the corresponding EELS data from the films has been done in a collective manner. The results from this study suggested even under nitrogen rich synthesis conditions carbon atoms in the B-C-N films prefer to be surrounded by other carbon atoms rather than boron and/or nitrogen. Furthermore, we have observed a similar behavior in the chemistry of B-C-N films deposited with increasing substrate bias conditions. In order to better understand these results, we have compared and evaluated the relative stability of various nearest-neighbor and structural configurations of carbon atoms in a single BN sheet using DFT calculations. These calculations also indicated that structures and configurations that increase the relative amount of C-C bonding with respect to B-C and/or C-N were energetically favorable than otherwise. As a conclusion, carbon tends to phase-segregate in to carbon clusters rather than displaying a homogeneous distribution for the films deposited in this study under the deposition conditions studied. (C) 2009 Elsevier B.V. All rights reserved.

Yerci, Selcuk/0000-0003-0599-588X; Serincan, Ugur/0000-0002-6305-4343; Serincan, Ugur/0000-0002-6305-4343; Dogan, Ilker/0000-0003-4245-787X WOS: 000241248000070 Silicon nanocrystals, average sizes ranging between 3 and 7 nm, were formed in sapphire matrix by ion implantation and subsequent annealing. Evolution of the nanocrystals was detected by Raman spectroscopy and x-ray diffraction (XRD). Raman spectra display that clusters in the matrix start to form nanocrystalline structures at annealing temperatures as low as 800 degrees C in samples with high dose Si implantation. The onset temperature of crystallization increases with decreasing dose. Raman spectroscopy and XRD reveal gradual transformation of Si clusters into crystalline form. Visible photoluminescence band appears following implantation and its intensity increases with subsequent annealing process. While the center of the peak does not shift, the intensity of the peak decreases with increasing dose. The origin of the observed photoluminescence is discussed in terms of radiation induced defects in the sapphire matrix. (c) 2006 American Institute of Physics.