LEED-investigations and work-function measurements of the first stages of epitaxy of tungsten on tungsten (110)

Abstract

The arrangement of tungsten atoms (0.2-4 mono layers) evaporated onto W(llO) has been studied with LEED and work-function measurements in ultrahigh vacuum. For temperatures of T = 300-430 K island growth has been derived from rings, which are visible at characteristic energies, around each spot of the LEED pattern. By increasing substrate temperature the islands coalesce in the [001] direction. For T = 520--800 K the surface shows microfacets with step edges in the [1 TO] direction.Step-free epitaxial growth has been observed at T = 950 K. The decrease of work function during evaporation confirms the formation of islands and facets. The average dipole moment per edge atom has been determined by combination ofLEED and work-function data. Quantitative evaluation of the LEED pattern yields the distance between islands, size of islands, and number of rows of atoms per terrace. The results show that the LEED pattern provides information on epitaxial growth which is not available with any other technique.

Off-specular reflectivity study of sputter-deposition of platinum during growth

“…This is similar to.the diffuse scattering previously observed for a growth of 'tungsten on tungsten by low-energy electron diffraction (LEED) measurements. [5] In this LEED study, the authors have attributed the ring diameter to the average distance between . I ' the islands.…”

Atomically precise impurity identification and modification on the manganese doped GaAs(110) surface with scanning tunneling microscopy

“…As usual for X-STM we first had to find the AlAs marker to make sure that we would scan the Mn doped layers. Then the Mn acceptors were identified by their well-known topographic contrast at around +1.5 V. 11 The exact voltage needed to address the Mn atoms depends on the microscopic configuration as well as the chemical composition of the tip apex ͑which sets the work function 23,24 of the tip͒. The voltage at which a specific contrast ͑e.g., the bow tie of a Mn atom͒ is addressed can thus differ by several hundred millivolts between individual atomic tip configurations.…”

High-resolution LEED profile analysis and diffusion barrier estimation for submonolayer homoepitaxy of Ag/Ag(100)

“…6 Such splitting was first observed and discussed in an experimental study of submonolayer W/W͑110͒ deposition by Hahn, Clabes, and Henzler. 7 A variety of simple, typically one-dimensional models for the adlayer statistics ͑e.g., specifying island size and separation distributions͒ have further clarified these ideas. 6 However, a precise quantitative analysis of diffraction profiles must be based upon an accurate description of the nontrivial spatial correlations characterizing the two-dimensional island distribution.…”