Al-alkyls as acceptor dopant precursors for atomic-scale devices

Area of Science:

• Materials Science
• Surface Chemistry
• Semiconductor Manufacturing

Background:

• Atomic precision advanced manufacturing (APAM) enables ultradoping of silicon using specific precursors.
• Current APAM precursor limitations restrict the range of dopants, particularly those with organic functional groups.

Purpose of the Study:

• To investigate the use of aluminum alkyls (trimethylaluminum and triethylaluminum) as precursors for ultradoping silicon with aluminum.
• To expand the applicability of APAM by incorporating organic functional group dopants.

Main Methods:

• Utilized scanning tunneling microscopy (STM) to analyze surface structures and impurity content.
• Employed density functional theory (DFT) calculations to model surface chemistry and incorporation mechanisms.
• Investigated ultradoping of Si(001) using a hydrogen mask with aluminum alkyl precursors.

Main Results:

• Assessed impurity content and selectivity for both trimethylaluminum and triethylaluminum precursors.
• Compared the impact of methyl and ethyl ligands on aluminum incorporation and surface chemistry.
• Identified limitations associated with each class of aluminum alkyl precursor.

Conclusions:

• Aluminum alkyls show potential for ultradoping silicon within the APAM framework.
• Understanding ligand effects is crucial for optimizing precursor selection in APAM.
• General principles for using organic functional group precursors in APAM were extracted.