Details

Autor(en) / Beteiligte

• Gerke, S.
• Becker, H.-W.
• Rogalla, D.
• Singer, F.
• Brinkmann, N.
• Fritz, S.
• Hammud, A.
• Keller, P.
• Skorka, D.
• Sommer, D.
• Weiß, C.
• Flege, S.
• Hahn, G.
• Job, R.
• Terheiden, B.

Titel

Influence of post-hydrogenation upon electrical, optical and structural properties of hydrogen-less sputter-deposited amorphous silicon

Ist Teil von

• Thin solid films, 2016-01, Vol.598, p.161-169

Ort / Verlag

Elsevier B.V

Erscheinungsjahr

2016

Link zum Volltext

Quelle

ScienceDirect Journals (5 years ago - present)

Beschreibungen/Notizen

• 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°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 5Ωcm, FZ, (n) c-Si can be achieved by post-hydrogenation yielding a minority carrier lifetime of ~360μs finding an optimum for ~40nm thin films, deposited at 325°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 E04) can be determined to ~1.88eV 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. •Post-hydrogenation of hydrogen-less RF sputter deposited a-Si•Hydrogen depth profiling of the ongoing post-hydrogenation process by NRRA•Determining diffusion coefficients of H and related diffusion mechanism•Analyze changes in elec., opt. and struct. properties of a-Si during post-hydro•Achieving surface passivation during post-hydrogenation of H-less deposited a-Si