Influence of post-hydrogenation upon electrical, optical and structural properties of hydrogen-less sputter-deposited amorphous silicon
| Autor: | Susanne Fritz, Reinhart Job, Sebastian Gerke, Daniel Sommer, Barbara Terheiden, Nils Brinkmann, Adnan Hammud, Florian Singer, Detlef Rogalla, Giso Hahn, Hans-Werner Becker, Daniel Skorka, Stefan Flege, Philipp Keller, Christof Weiß |
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| Přispěvatelé: | Publica |
| Rok vydání: | 2016 |
| Předmět: |
Amorphous silicon
Materials science Hydrogen Passivation chemistry.chemical_element Nanotechnology 02 engineering and technology 01 natural sciences chemistry.chemical_compound Sputtering 0103 physical sciences Materials Chemistry ddc:530 Thin film 010302 applied physics business.industry Doping Metals and Alloys Surfaces and Interfaces Carrier lifetime 021001 nanoscience & nanotechnology AFM Amorphous silicon Hydrogen depth profiling NRRA Post-hydrogenation Raman RF sputter-deposition Surfaces Coatings and Films Electronic Optical and Magnetic Materials Amorphous solid chemistry Optoelectronics 0210 nano-technology business |
| Zdroj: | Thin Solid Films. 598:161-169 |
| ISSN: | 0040-6090 |
| DOI: | 10.1016/j.tsf.2015.11.063 |
| Popis: | Amorphous silicon (a-Si) is common in the production of technical devices and can be deposited by several techniques. In this study 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 degrees C. Secondary ion mass spectrometry of a boron doped (p) a-Si layer shows that the concentration of dopants in the sputtered layer becomes the same as present in the sputter-target. Improved surface passivation of phosphorous doped 5 Omega cm, FZ, (n) c-Si can be achieved by post-hydrogenation yielding a minority carrier lifetime of similar to 360 mu s finding an optimum for similar to 40 nm thin films, deposited at 325 degrees C. This relatively low minority carrier lifetime indicates high disorder of the hydrogen-less sputter deposited amorphous network. Post-hydrogenation leads to a decrease of the number of localized states within the band gap. Optical band gaps (Taucs gab as well as E-04) can be determined to similar to 1.88 eV after post-hydrogenation. High resolution transmission electron microscopy and optical Raman investigations show that the sputtered layers are amorphous and stay like this during post-hydrogenation. As a consequence of the missing hydrogen during deposition, sputtered a-Si forms a rough surface compared to CVD a-Si. Atomic force microscopy points out that the roughness decreases by up to 25% during post-hydrogenation. Nuclear resonant reaction analysis permits the investigation of hydrogen depth profiles and allows determining the diffusion coefficients of several post-hydrogenated samples from of a model developed within this work. A dependency of diffusion coefficients on the duration of post-hydrogenation indicates trapping diffusion as the main diffusion mechanism. Additional Fourier transform infrared spectroscopy measurements show that hardly any interstitial hydrogen exists in the post-hydrogenated a-Si layers. The results of this study open the way for further hydrogen diffusion experiments which require an initially unhydrogenated drain layer. |
| Databáze: | OpenAIRE |
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