Surface diffusion of Sb on Ge(111) investigated by second harmonic microscopy

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:5528204

Schultz, K A

Surface diffusion of Sb on Ge(111) has been measured with the newly-developed technique of second harmonic microscopy. In this method, concentration profiles at submonolayer coverage are imaged directly by second harmonic generation with 5 [mu]m spatial resolution. A Boltzmann-Matano analysis of the concentration profiles yields the coverage dependence of the diffusivity D without parameterization. Experiments were performed at roughly 70% of the bulk melting temperature T[sub m]. In the coverage range of 0 < [theta] < 0.6, the activation energy E[sub diff] remains constant at 47.5 [+-] 1.5 kcal/mol. The corresponding pre-exponential factor decreases from 8.7 [times] 10[sup 3[+-]0.4] to 1.6 [times] 10[sup 2[+-]0.4] cm[sup 2]/sec. The results are explained in terms of a new vacancy model for surface diffusion at high-temperatures. The model accounts semiquantitatively for the large values of E[sub diff] and D[sub o], and suggest that these quantities may be manipulated by bulk doping levels and photon illumination of the surface.

• Research Organization: Illinois Univ., Urbana, IL (United States)
• OSTI ID: 5528204
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360601* -- Other Materials-- Preparation &amp; Manufacture
665000 -- Physics of Condensed Matter-- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANTIMONY
CRYSTAL DEFECTS
CRYSTAL DOPING
CRYSTAL STRUCTURE
DIFFUSION
ELEMENTS
FREQUENCY MIXING
GERMANIUM
HARMONIC GENERATION
METALS
MICROSCOPY
POINT DEFECTS
SURFACE PROPERTIES
VACANCIES