Engineering topics

Fan, W. C.

Publications and source records attributed to Fan, W. C..

4 records

NASA NTRS1992

Reflection high-energy electron diffraction study of growth and interface formation of the Ga(1-x)In(x)Sb/InAs strained-layer superlattices

Reflection high-energy electron diffraction (RHEED) during molecular beam epitaxy is used to study the growth and interface formation of the Ga(1-x)In(x)Sb/InAs (x is not greater than 0.4) strained-layer superlattices (SLSs) on GaSb(100) substrates. A number of surface atomic structures were observed in the growth of the SLS: a (1 x 3) phase from the InAs epilayer surface, a (2 x 3) phase, a (2 x 4) phase, and diffuse (1 x 1)-like phases from the InAs epilayer surface. It is suggested that the long-range order quality of the interface of Ga(1-x)In(x)Sb on InAs may be better than that of the interface of InAs on Ga(1-x)In(x)Sb, but the abruptness of the interfaces would still be compatible. The RHEED intensity variations in the formation of the interfaces are discussed in terms of interface chemical reactions.

Fan, W. C.↗

NASA NTRS1991

Y1Ba2Cu3O(6+delta) growth on thin Y-enhanced SiO2 buffer layers on silicon

SiO2 buffer layers as thin as 2 nm have been developed for use in the growth of Y1Ba2Cu3O(6+delta) thin films on silicon substrates. The SiO2 layers are formed through Y enhancement of silicon oxidation, and are highly stoichiometric. Y1Ba2Cu3O(6+delta) film growth on silicon with thin buffer layers has shown c orientation and Tc0 = 78 K.

Robin, T.↗

NASA NTRS1990

The effect of Sr and Bi on the Si(100) surface oxidation - Auger electron spectroscopy, low energy electron diffraction, and X-ray photoelectron spectroscopy study

The effect of Sr and Bi on the oxidation of the Si(100) surface has been studied by Auger electron spectroscopy, low electron diffraction, and X-ray photoelectron spectroscopy. A dramatic enhancement, by a factor of 10, of the Si oxidation has been observed for Si(100) with a Sr overlayer. The SR-enhanced Si oxidation has been studied as a function of O2 exposure and Sr coverage. In contrast to the oxidation promotion of Sr on Si, it has been also observed that a Bi overlayer on Si(100) reduced Si oxidation significantly. Sr adsorption on the Si(100) with a Bi overlayer enhances Si oxidation only at Sr coverage of greater than 0.3 ML.

Fan, W. C.↗

NASA NTRS1990

Oxidation of the Si(100) surface promoted by Sr overlayer - An X-ray photoemission study

The interaction of strontium films with the underlaying Si (100) surface and the Sr-promoted low-temperature oxidation of Si were investigated, using XPS, at three different Sr coverages (theta): theta = 0.55 monolayer (ML), theta = 1 ML, and theta = 1.85 ML. Oxygen adsorption was studied both at room temperature and at 500 C, and at oxygen exposures up to 2 x 10 to the 6th L (1 L = 10 to the -6th torr) and 2 x 10 to the 5th L, respectively. The XPS spectra of the Si2p, O1s, and Sr3d core levels were measured for the atomically clean Si, the Sr-covered Si, and for the Sr-covered Si after each oxygen exposure. Results indicate that Sr interacts with the Si(100) surface forming a strong ionic bond, and that Sr promotes the oxidation of the Si (100) surface.

Mesarwi, A.↗