Rapid growth of nanostructure on tungsten thin film by exposure to helium plasma

A fiberform nanostructure was synthesized by exposing high-density helium plasma to a 100 nm thick tungsten thin film in the linear plasma device NAGDIS-II.After helium plasma exposure,the cross-section of samples was observed by a scanning electron microscope,transmission electron microscope,and focused ion beam scanning electron microscope.It is shown that the thickness of the nanostructured layer increases significantly for only a short irradiation time.The optical absorptivity remains high,even though it is exposed to helium plasma for a short time.The usage of the thin film can shorten the processing time for nanostructure growth,which will be beneficial for commercial production.

Modeling of the impurity-induced silicon nanocone growth by low energy helium plasma irradiation

The formation mechanism of nanocone structure on silicon(Si)surface irradiated by helium plasma has been investigated by experiments and simulations.Impurity(molybdenum)aggregated as shields on Si was found to be a key factor to form a high density of nanocone in our previous study.Here to concrete this theory,a simulation work has been developed with SURO code based on the impurity concentration measurement of the nanocones by using electron dispersive x-ray spectroscopy.The formation process of the nanocone from a flat surface was presented.The modeling structure under an inclining ion incident direction was in good agreement with the experimental result.Moreover,the redeposition effect was proposed as another important process of nanocone formation based on results from the comparison of the cone diameter and sputtering yield between cases with and without the redeposition effect.

Comparison of Damages on Tungsten Surface Exposed to Noble Gas Plasmas

Tungsten was exposed to pure Ar or Ne plasmas over 1550 K at several incident ion energies. Even under the irradiation condition that the tungsten nanostructure is formed by He plasma irradiation, holes/bubbles and fiberform nanostructures were not formed on the surface by exposure to Ar or Ne plasmas. In addition, the results from energy dispersive X-ray spectroscopy supported the facts that Ar and Ne did not remain in the sample. We will discuss the reason for the differences in the damage to the tungsten surface exposed to noble gas plasmas.

Diagnostics of Rovibrational Distribution of H_2 in Low Temperature Plasmas by Fulcher-α band Spectroscopy - on the Reaction Rates and Transition Probabilities

A novel fitting procedure is proposed for a better determination of H2 rovibrational distribution from the Fulcher-α band spectroscopy. We have recalculated the transition probabilities and the results show that they deviate from Franck-Condon approximation especially for the non-diagonal transitions. We also calculated the complete sets of vibrationally resolved cross sections for electron impact d3Ⅱu-X3Σg transition based on the semi-classical Gryzinski theory. An example of experimental study confirms that current approach provides a tool for a better diagnostics of H2 rovibrational distribution in electronic ground state.