Influence of post-hydrogenation upon electrical, optical and structural properties of hydrogen-less sputter-deposited amorphous silicon
TL;DR: In this article, an intrinsic and doped, hydrogen-less amorphous silicon films are RF magnetron sputter deposited and post-hydrogenated in a remote hydrogen plasma reactor at a temperature of 370°C.
About: This article is published in Thin Solid Films.The article was published on 2016-01-01 and is currently open access. It has received 9 citations till now. The article focuses on the topics: Amorphous solid & Amorphous silicon.
Summary (1 min read)
2.2. Passivation quality
- Passivation quality and evaluation during post hydrogenation of RFS deposited a Si:H is done by means of effective minority carrier lifetime (τ eff ) measurements.
- These are carried out at room temperature (~25 °C) via microwave detected photo conductance decay measure ments (μPCD) using a Semilab WT 2000 with a spatial resolution of 250 μm and bias light of 1 sun.
- Spatially resolved τ eff data are providing detailed information about the local influence of the post hydrogenation and the homogeneity of the film.
- Measurements are cross checked via τ eff deduction from transient and quasi steady state photo conductance decay (WCT 120, Sinton Instruments), also at ~25 °C.
3.4. Structural stability
- Raman investigations demonstrate that there is no crystallization occurring during post hydrogenation (4>, = 0%).
- Moreover, it is shown that the (i) and (p) a Sl surfaces investigated by AFM (Fig. 6 ) and the discussed nano sized structures are also amorphous.
4. Conclusions
- The investigations in this study demonstrated that initially hydrogen less and non passivating intrinsic as well as doped a Si layers develop surface passivation properties during a post hydrogenation step in a MIRHP reactor at 370 °C.
- These optimal lifetime values are achieved with layer thicknesses of ~40 nm deposited at a temperature of 325 °C.
- This can be related to a decrease of localized states within the band gap.
- The surface roughness of the initially rough RFSD a Si decreases up to 25% during post hydrogenation while the Raman crystallinity remains at 0%, indicating the stability of the amorphous network.
- This suggests a columnar growth of the RFS deposited a Si.
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TL;DR: In this article, the porosity of underdense a-Si:H layer enables H penetration into the amorphous network and the Si:H/c-Si interface.
Abstract: Underdense hydrogenated amorphous silicon (a-Si:H) prepared by plasma-enhanced chemical vapor deposition was used as a passivation layer in silicon heterojunction (SHJ) solar cells. By reducing the thickness of the underdense a-Si:H passivation layer from 15 nm to 5 nm, the open circuit voltage (Voc) of the corresponding SHJ solar cell increased significantly from 724.3 mV to 738.6 mV. For comparison, a widely used transition-zone a-Si:H passivation layer was also examined, but reducing its thickness from 15 nm to 5 nm resulted in a continuous Voc reduction, from 724.1 mV to 704.3 mV. The highest efficiency was achieved using a 5-nm-thick underdense a-Si:H passivation layer. We propose that this advantageous property of underdense a-Si:H reflects its microstructural characteristics. While the porosity of a-Si:H layer enables H penetration into the amorphous network and the a-Si:H/c-Si interface, a high degree of disorder inhibits the formation of the epitaxial layer at the a-Si:H/c-Si interface during pos...
45 citations
TL;DR: The manuscript reviews several selected applications of Activation Analysis that differ from classical laboratory measurements by the fact that they do not require sampling of the analysed object and/or measurements under analytical laboratory conditions.
Abstract: The manuscript reviews several selected applications of Activation Analysis that differ from classical laboratory measurements by the fact that they do not require sampling of the analysed object and/or measurements under analytical laboratory conditions. One of great advantages of the Activation Analysis lies in its versatility that allows it to be applied under conditions not available for other analytical techniques.
15 citations
TL;DR: In this paper, bias-plasma assisted radio frequency magnetron sputter deposition (RFSD) is used to flatten the a-Si surface of the film, resulting in an amorphous network with only few vacancies and related defects.
7 citations
Cites background or methods from "Influence of post-hydrogenation upo..."
...Furthermore, analyzing formerly hydrogen-less a-Si during a post-hydrogenation step allows determining hydrogen related influences on electrical, optical and structural characteristics [3]....
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...Bias-plasma assisted as well as standard RFS-deposition takes place in an “AJA ATC 2200” RF magnetron sputtering system....
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...The abrasive process of BPA-RFS-deposition smoothening the surface of the growing (i) a-Si layer can be used for surface preparation prior to deposition....
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...[3], the investigation of the progress of hydrogen based saturation of defects like dangling bonds and the related reduction of surface recombination velocity with post-hydrogenation duration can be evaluated by effective minority carrier lifetime measurements ( eff)....
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...2 (a) shows i. a. the evolution of eff after the mentioned post-hydrogenation step of (i) a-Si layers, RFS-deposited with ( ) and without ( ) bias-plasma assistance and as a function of RFS-deposition temperature....
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01 Jan 2019
TL;DR: In this article, the main focus is on physical vapor deposition techniques, with special emphasis on plasma processing techniques, i.e., sputter deposition and pulsed laser deposition, as well as ion plating and ion beam-assisted deposition.
Abstract: This chapter is devoted to the description of available experimental methods which are used for the fabrication of glassy and amorphous thin films or coatings on glass. Current deposition techniques offer great flexibility for the fabrication of such thin films with specific chemistry and microstructure leading to films and coatings with distinctive properties. After a brief introduction to amorphous thin films' processing, general information regarding film nucleation and growth, its microstructure and films' characterization techniques, the main focus is on physical vapor deposition techniques, with special emphasis on plasma processing techniques, i. e., sputter deposition and pulsed laser deposition. The classical vapor deposition techniques as well as ion plating and ion beam-assisted deposition are also briefly described. The chapter then describes the exploitation of chemical vapor deposition, after which a comparison of physical vapor deposition processes with chemical vapor deposition is given. Amorphous thin film fabrication via liquids is shortly reviewed, and finally an outlook regarding the contribution of amorphous thin films and coatings to societal development in the 21st century closes the chapter.
6 citations
References
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TL;DR: The atomic force microscope as mentioned in this paper is a combination of the principles of the scanning tunneling microscope and the stylus profilometer, which was proposed as a method to measure forces as small as 10-18 N. As one application for this concept, they introduce a new type of microscope capable of investigating surfaces of insulators on an atomic scale.
Abstract: The scanning tunneling microscope is proposed as a method to measure forces as small as 10-18 N. As one application for this concept, we introduce a new type of microscope capable of investigating surfaces of insulators on an atomic scale. The atomic force microscope is a combination of the principles of the scanning tunneling microscope and the stylus profilometer. It incorporates a probe that does not damage the surface. Our preliminary results in air demonstrate a lateral resolution of 30 A and a vertical resolution less than 1 A.
12,344 citations
Book•
04 Jul 1990
TL;DR: In this article, the authors present a characterization of the resistivity of a two-point-versus-four-point probe in terms of the number of contacts and the amount of contacts in the probe.
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"Influence of post-hydrogenation upo..." refers methods in this paper
...6 Ω cm (in house measured by the 4 Point Probe method [23])....
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