講演情報
[19p-A202-7]Tungsten fuzzy structure formation at lower temperature (< 900 K)
〇(PC)Quan Shi1, Shin Kajita2, Noriyasu Ohno3 (1.NIFS, 2.Univ. of Tokyo, 3.Nagoya Univ.)
キーワード：
fuzzy nano-structure、tungsten
Fiber-form nanostructures, referred to as fuzz, formed on pure tungsten (W) have been widely reported in the research of helium (He) plasma and wall material interactions. Recently, using a thin film (100 nm in thickness) of W on a glass substrate, the growth speed of fuzz can be significantly increased. This brings up a deeper discussion about the mechanism of fuzz formation. In this study, we performed He plasma irradiation together with W deposition (co-deposition) on silicon (Si) samples.
The deposition source was a W wire with negative bias located 10 mm in front of the Si substrate. First, co-deposition experiments were conducted on Si substrates with flat surfaces. Fuzz can be formed if the deposition rate is high enough. And the growth rate of fuzz in relation to He fluence and the formation temperature threshold (900 K) are almost the same as on the pure W substrate. However, if the Si substrate is covered by nanocone structures the formation temperature threshold can be reduced to 800 K. Components of the fuzzy structure are confirmed as pure W by X-ray photoelectron spectroscopy. It is probably because that the growth process of fuzz on a rough surface requires only 800 K of temperature, but the surface roughening processes of pure W, such as He bubble formation and rupture, need temperatures over 900 K. The mild conditions to fabricate fuzzy structures also benefit commercial manufacturing.
The deposition source was a W wire with negative bias located 10 mm in front of the Si substrate. First, co-deposition experiments were conducted on Si substrates with flat surfaces. Fuzz can be formed if the deposition rate is high enough. And the growth rate of fuzz in relation to He fluence and the formation temperature threshold (900 K) are almost the same as on the pure W substrate. However, if the Si substrate is covered by nanocone structures the formation temperature threshold can be reduced to 800 K. Components of the fuzzy structure are confirmed as pure W by X-ray photoelectron spectroscopy. It is probably because that the growth process of fuzz on a rough surface requires only 800 K of temperature, but the surface roughening processes of pure W, such as He bubble formation and rupture, need temperatures over 900 K. The mild conditions to fabricate fuzzy structures also benefit commercial manufacturing.