Lead growth on Si(111) surfaces reconstructed by indium

Area of Science:

• Surface Science
• Materials Science
• Condensed Matter Physics

Background:

• Understanding thin film growth is crucial for developing novel electronic and magnetic materials.
• The Si(111) surface exhibits various reconstructions, such as √3 × √3-In and 4 × 1-In, which can influence adatom behavior.
• The role of substrate reconstruction and temperature in determining the growth mode and electronic properties of lead (Pb) films on Si(111) requires detailed investigation.

Purpose of the Study:

• To investigate the growth mode of Pb on Si(111) surfaces with different reconstructions (√3 × √3-In and 4 × 1-In).
• To explore the influence of substrate reconstruction and temperature on the morphology and electronic structure of Pb films.
• To establish correlations between growth characteristics and the resulting electronic properties of Pb films.

Main Methods:

• Complementary surface science techniques were employed, including Auger electron spectroscopy (AES), low energy electron diffraction (LEED), soft x-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy (STM), and spot profile analysis-low energy electron diffraction (SPA-LEED).
• Pb growth was studied on both √3 × √3-In and 4 × 1-In reconstructed Si(111) surfaces at room temperature and 160 K.
• Analysis focused on growth morphology, electronic structure, and adatom bonding arrangements.

Main Results:

• On Si(111)√3 × √3-In at low temperature, Pb formed 3D islands with poor crystallinity on a wetting layer, preserving the substrate's semiconducting nature.
• On Si(111)4 × 1-In at low temperature, Pb formed metallic, crystalline Pb(111) islands after a double incomplete wetting layer, exhibiting enhanced Pb-Pb interaction and metallization.
• The stronger interaction of In with Si compared to Pb-Si promoted Pb metallization. Quantum size effects influenced island formation, and the 4 × 1-In interface offered better decoupling, leading to thermally stable islands.

Conclusions:

• Substrate reconstruction plays a critical role in determining Pb growth mode, morphology, and electronic properties on Si(111).
• The Si(111)4 × 1-In surface facilitates the growth of metallic, crystalline Pb films with enhanced thermal stability due to quantum size effects and improved decoupling.
• Tailoring the initial substrate reconstruction offers a pathway to control the growth and electronic characteristics of Pb films.