Texture of Polycrystalline MoS x Thin Films Magnetron Sputtered from a Metallic Target in Ar-H 2 S Atmospheres
- PDF / 2,420,969 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 4 Downloads / 163 Views
Texture of Polycrystalline MoSx Thin Films Magnetron Sputtered from a Metallic Target in Ar-H2S Atmospheres Volkmar Weiß, Rainald Mientus1 and Klaus Ellmer Hahn-Meitner-Institut Berlin, Dept. Solare Energetik, Glienicker Str. 100, D-14109 Berlin, Germany. 1 Optotransmitter-Umweltschutz-Technologie e.V., Köpenicker Str. 325b, D-12555 Berlin, Germany.
ABSTRACT The textured film growth of polycrystalline MoSx films on Si substrates deposited by reactive magnetron sputtering with H2S from a molybdenum target has been investigated. Over a wide range of gas flow ratios FH2S/(FH2S+FAr) from 1% to 75% only x-ray diffraction patterns of randomly stacked S-Mo-S layers of the MoS2 phase were detected which indicates turbostratic growth of the van-der-Waals layers comparable to the growth of graphite at low temperatures. The extended distance of the c-lattice planes depends on the sputtering conditions and can also be explained by the turbostratic model. Low deposition rates and high substrate temperatures improved the quality of the films towards the requested (001) texture and low c-lattice strain. The results from the in situ-energy dispersive x-ray diffraction (EDXRD) technique using synchrotron radiation allowed kinetic calculations of the time dependent behaviour of the peak area of the (0 0 2l) Bragg reflection signals according to the Johnson-Mehl-Avrami model. They revealed that the grain growth is restricted in dimensions if a completed nucleation is assumed.
INTRODUCTION Van-der-Waals-layer type semiconductors MX2 (M = Mo, W; X = S, Se) have been proposed as absorber materials for thin film solar cells [1]. Studies have shown that the texture of thin films of these materials is an important factor for their photoactivity [2-4]. The (001) texture, where the van-der-Waals planes are parallel to the substrate surface, is favoured for the application in solar cells because such films have less surface states which can act as charge carrier recombination centres. Since reactive magnetron sputtering from metallic targets in mixtures of argon and a reactive gas (e.g. O2, H2, H2S) is a well established technique for thin film deposition of oxides and sulfides [5] we investigated this method for the deposition of MoSx films. In order to understand the growth mechanisms in situ experiments with energy dispersive x-ray diffraction (EDXRD) during the sputtering process were performed at the synchrotron radiation source HASYLAB at Hamburg, Germany.
J5.3.1 Downloaded from https://www.cambridge.org/core. Access paid by the UCSB Libraries, on 14 May 2018 at 21:31:44, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1557/PROC-721-J5.3
EXPERIMENTAL DETAILS The depositions have been carried out in a load lock sputtering chamber with a 2 ” balanced magnetron sputtering source. This chamber was designed for in situ-EDXRD experiments at the synchrotron radiation source HASYLAB as described in ref. 6. The films have been deposited by reactive sputtering from a molybdenum
Data Loading...
