Electron and lattice structure of ultra thin Ag films on Si(111) and Si(001)

TL;DR

This study investigates the atomic structure, morphology, and electronic properties of ultra-thin silver films grown on Si(111) and Si(001) surfaces at low temperatures, revealing unique surface reconstructions and growth behaviors.

Contribution

It provides new insights into the growth mechanisms and surface structures of ultra-thin Ag films on silicon, including the observation of a (root3xroot3)R30^o LEED pattern and epitaxial twinned growth.

Findings

Ag films form sharp islands and flat terraces on Si(111)

Epitaxial twinned Ag(111) growth occurs on Si(001) at low coverage

Conductivity measurements show temperature-dependent behavior of ultra-thin Ag films

Abstract

We studied the low temperature (T<130K) growth of Ag on Si(001) and Si(111) flat surfaces prepared by Si homo epitaxy with the aim to achieve thin metallic films. The band structure and morphology of the Ag overlayers have been investigated by means of XPS, UPS, LEED, STM and STS. Surprisingly a (root3xroot3)R30^o LEED structure for Ag films has been observed after deposition of 2-6 ML Ag onto a Si(111)(root3xroot3)R30^o Ag surface at low temperatures. XPS investigations showed that these films are solid, and UPS measurements indicate that they are metallic. However, after closer STM studies we found that these films consists of sharp Ag islands and (root3xroot3)R30^o Ag flat terraces in between. On Si(001) the low-temperature deposition yields an epitaxial growth of Ag on clean Si(001)2x1 with a twinned Ag(111) structure at coverages as low as 10 ML. Furthermore the conductivity of few monolayer Ag films on Si(100) surfaces has been studied as a function of temperature (40-300 K).