Controlling the work function of recording head materials through fluorination with XeF2

ANA TARDITI, PETER KONDRATYUK, ANDREW J. GELLMAN

Carnegie Mellon University, Pittsburgh Pensilvania USA

Conferencia; DSSC; 2008

Data Storage Systems Center, Carnegie Mellon University

Electric charging can occur during the operation of magnetic recording heads dueelectron transfer from the head to the underlying disk surface. The work function (F) ofthe recording head material acts as a barrier to electron transfer, and thus directlyimpacts the extent of the charging.As a means of modifying the work function, we subjected the carbon film-covered surfaceto fluorination with XeF2 under ultrahigh vacuum (UHV) conditions. Introduction ofelectronegative species such as fluorine is known to raise the work function by creating anegatively-charged surface layer. The changes in surface composition were monitoredwith X-ray photoemission spectroscopy (XPS), while the work function was measuredwith UV photoemission spectroscopy (UPS).We find that fluorination with XeF2 increases the work function of the diamond-like carbon(DLC) layer by as much as 1.5 eV. In addition, most of the increase occurs at very lowsurface concentrations of fluorine, suggesting that a small number of highly reactive DLCsites have a controlling influence with respect to the surface work function.The effect of fluorination can be reversed by annealing the sample at high temperatures,leading to the loss of surface fluorine.