Bandgap shifting and crystalline quality of RF-sputtered intrinsic-ZnO nanofilm for TFSC application

Link to publisher's homepage at http://ijneam.unimap.edu.myIntrinsic Zinc Oxide (i-ZnO) is a promising material and has been applied in many types of solar cell structures, and particularly in thin film solar cells (TFSC) where it is normally used as the n-type layer or as normally addressed, the buffer or window layer. In this work, ZnO nanofilm was deposited by radio frequency (RF) sputtering technique and the thickness was varied in the range of 50 to 200 nm. The overall results show that the average transmission of i-ZnO was over 70% and the band gap (Eg) obtained was in the range of 3.14 eV-3.25 eV for all nanofilms. Meanwhile, for the structural results, it was clearly shown that the crystalline size of the nanofilms have good quality, and all ZnO films exhibited a (002) diffraction peak, proving the crystallinity of the films via x-ray diffraction (XRD) data analysis. The results assume that the ZnO with various thicknesses deposited with this technique were in accordance with its expected properties and is acceptable to be utilized in TFSC application as a buffer or window layer

Spin-coated CZTS films prepared by two different precursor mixing regimes, at room temperature and at 150 °C

In this paper, we examine the impact of the precursor's mixing temperature and mixing protocol on the crystal structure and morphological and optical properties of Cu2ZnSnS4 (CZTS) thin films. Four samples of CZTS thin films were synthesized with the sol-gel spin coating technique by previously mixing precursors at (a) 150 °C and (b) room temperature (RT), either (i) all at once or (ii) through sequential adding the individual chemicals 30 min apart. SEM-EDX, XRD, Raman and Visible spectroscopy analysis showed that sample 150°C-ST (chemicals mixed at the same time at 150 °C) fulfilled all the theoretical stoichiometric criteria (poor in Cu, rich in Zn) for the high-quality CZTS absorbers. The larger grain size (850 nm) and crystallite size (73.96 nm), lower strain (0.49×10−3) and band gap Eg=1.44eV which is closest to the Shockley–Queisser limit for single junction solar cells (1.34 eV)

An Investigation on Structural and Electrical Properties of RF-Sputtered Molybdenum Thin Film Deposited on Different Substrates

AbstractMolybdenum (Mo) is the prominent choice as the back contact for various thin film solar cells such as CIGS, CZTS and CdTe. Physical vapour deposition (PVD) technique especially sputtering process has been chosen as the foremost method to deposit Mo thin film on top of desired substrate due to ease of parametric control of growth conditions. In this paper, we reported the effect of various RF power, operating pressure as well as temperature on Mo films on top of Mo sheet and soda lime glass (SLG) deposited using RF magnetron sputtering. Uniform surface morphology was obtained as RF power, operating pressure and deposition temperature were optimised. However, at higher deposition temperature less uniform surface was observed. XRD pattern of Mo films showed two different peak of <200> and <211> in case of Mo sheet and single peak <110> in case of SLG. While peak intensity varies as deposition condition varies in case of Mo films deposited on Mo sheet. Electrical properties of Mo films on both Mo sheet and SLG were improved as RF power and deposition temperature are optimised. On the other hand, electrical properties are affected as operating pressure increased. Lower resistivity of 1.2x10-9Ω.m and 6.65x10-6Ω.m were found in case of Mo films deposited on Mo sheet and SLG. Surface roughness of 0.017 nm-19.32nm were found in case of Mo films deposited on Mo sheet and 0.002 nm-5.04nm were found in case of SLG. Roughness increased as RF power and deposition temperature increased. However, roughness decreased as operating pressure increased

Effect of Annealing on the Properties of ZnxCd1-xS Thin Film Growth by RF Magnetron Co-sputtering

AbstractZnxCd1-xS thin films at low zinc content have been deposited on bare soda lime glass substrates using RF magnetron co-sputtering of CdS and ZnS for the first time to investigate annealing effect on the structural and optical properties of the thin films. The as-deposited films were annealed in O2/N2 ambient at annealing temperature ranging 200-500°C. The composition of the films was controlled by varying RF power of CdS and ZnS in such a ratio so that zinc content in the thin films was low. The composition, structural, optical and surface morphological properties of the films was investigated using EDX, XRD, UV-Vis spectrophotometer and FESEM. The annealed films were observed hexagonal wurtzite structure with strong preferential orientation along (002) diffraction peak. Crystallinity of the films increased with increasing annealing temperature below 400°C whereas beyond 400°C new peaks were observed along with decreasing trend of (002) diffraction peak. Optical absorption and transmission spectra were recorded within the range 300-900nm. With increasing annealing temperature, the band gap of the annealed films once decreased and then abruptly increased at around 400°C. The decreased bandgap may have been due to possible increase in the crystalline nature of the material. From SEM, it was observed that the thin films were formed by different clusters of grains which later changed to isolated grains as the annealing temperature increased. This work confirms that annealing temperature has overbearing influence on the ZnxCd1-xS thin film properties deposited by RF magnetron co-sputtering