دانلود رایگان مقاله پردازش دمای پایین پلاسما برای ساخت غشا های نازک

Abstract

The recent bio-applications (i.e. bio-sensing, tissue engineering and cell proliferation etc.) are driving the fundamental research in carbon based materials with functional perspectives. High stability in carbon based coatings usually demands the high density deposition. However, the standard techniques, used for the large area and high throughput deposition of crystalline carbon films, often require very high temperature processing (typically >800 °C in inert atmosphere). Here, we present a low temperature (<150 °C) pulsed-DC plasma sputtering process, which enables sufficient ion flux to deposit dense unhydrogenated carbon thin films without any need of substrate-bias or post-deposition thermal treatments. It is found that the control over plasma power density and pulsed frequency governs the density and kinetic energy of carbon ions participating during the film growth. Subsequently, it controls the contents of sp3 and sp2 hybridizations via conversion of sp2 to sp3 hybridization by ion's energy relaxation. The role of plasma parameters on the chemical and surface properties are presented and correlated to the bio-activity. Bioactivity tests, carried out in mouse fibroblast L-929 and Sarcoma osteogenic (Saos-2) bone cell lines, demonstrate promising cell-proliferation in these films.

4. Conclusions

Low temperature carbon film fabrication is a processing challenge when one considers its use for large area deposition with high throughput. In present work, we have shown good quality carbon films with pulse DC plasma processing assisted with rotating substrate platform which restricts the substrate temperature well below 150
C. The correlation of plasma parameters to the control of sp3 and sp2 hybridization has been established on the basis of detailed core level study of the films. The role of power density is found to control the plasma density, where as the role of pulse frequency is found to enhance the ionization and kinetic energies of ions/neutrals during the film deposition. These low-temperature processed carbon films show excellent cell-viability for the L-929 mouse fibroblast and Saos-2 bone cells.