Biomedical subjects

MC Tringides

Publications and source records attributed to MC Tringides.

11 recordsLinked to original sources

PubMed2000

Role of the Metal/Semiconductor interface in quantum size effects: Pb /Si(111)

Self-organized islands of uniform heights can form at low temperatures on metal/semiconductor systems as a result of quantum size effects, i.e., the occupation of discrete electron energy levels in the film. We compare the growth mode on two different substrates [Si(111)- (7x7) vs Si(111)- Pb(sqrt[3]xsqrt[3] )] with spot profile analysis low-energy electron diffraction. For the same growth conditions (of coverage and temperature) 7-step islands are the most stable islands on the (7x7) phase, while 5-step (but larger islands) are the most stable islands on the (sqrt[3]xsqrt[3] ). A theoretical calculation suggests that the height selection on the two interfaces can be attributed to the amount of charge transfer at the interface.

Journal Article↗

PubMed2000

Determination of interlayer diffusion parameters for Ag/Ag(111)

It is well known that the Ag/Ag(111) epitaxial system grows three dimensionally because of the existence of a relatively high excess diffusion barrier, DeltaE(s) = 0.13 eV, at the step edges. Several experimental methods have been developed to measure the step edge barrier in this system over a wide coverage range. The probability for an atom to move from a higher to a lower layer depends on both the barrier and the prefactor, so it is important to test whether the prefactors for hopping over a step, nu(s), and for hopping on a terrace, nu(t), are different. We present the results from several experiments on Ag/Ag(111) to conclude that nu(s)/nu(t) = 10(2.0+/-0. 3).

Journal Article↗

PubMed2000

Correlations between the scanning tunneling microscopy imaged configurations and the electronic structure on stepped Si(111)-( 7x7) surfaces

We have observed the dependence of the scanning tunneling microscopy (STM) imaged atom intensity within the (7x7) unit cell on stepped Si(111) as a function of the tunneling voltage. Pronounced differences from the corresponding atom intensity on the flat surface are observed for the contrast of atoms on the low versus the high side of the step and for the contrast between the faulted versus unfaulted subcells of the (7x7) structure. These differences can be accounted for by changes in the electronic structure within the (7x7) subcells adjacent to the step. Calculations of the local density of states and the STM images using a tight-binding method are in excellent agreement with the experimental results.

Journal Article↗

PubMed1994