Boosting the Boron Dopant Level in Monolayer Doping by Carboranes

Area of Science:

• Materials Science
• Semiconductor Physics
• Surface Chemistry

Background:

• Monolayer doping (MLD) offers a damage-free alternative for silicon doping, enabling ultrashallow junctions and doping of complex surfaces.
• Current MLD methods utilize dopant-containing alkenes via hydrosilylation, but achieving high doping levels remains a challenge.

Purpose of the Study:

• To enhance monolayer doping (MLD) efficiency by designing alkenes with a high dopant atom content.
• To demonstrate significantly increased silicon doping levels using novel carborane-derived alkenes.

Main Methods:

• Functionalization of carborane derivatives (containing 10 boron atoms per molecule) with alkene groups.
• Application of these functionalized molecules to silicon surfaces via MLD using hydrosilylation.
• Characterization of doping levels using X-ray photoelectron spectroscopy (XPS) and dynamic secondary mass spectrometry (DSMS).
• Evaluation of electrical properties through sheet resistance measurements.

Main Results:

• MLD using carborane derivatives achieved up to ten times higher doping levels compared to single-boron-atom alkenes.
• Increased doping levels directly correlated with enhanced conductivity of silicon substrates.
• Thermal budget analysis suggests further optimization of doping levels is possible through annealing conditions.

Conclusions:

• Designing alkenes with high dopant density is a viable strategy to significantly boost MLD efficiency.
• This approach provides a pathway for achieving high-performance silicon doping without crystal damage.
• Further optimization of annealing processes can refine doping levels for specific applications.