Electronic Control of Silicon Surface Atomic Structures with Two-Probe Scanning Tunneling Microscopy.

Area of Science:

• Surface Science
• Materials Science
• Nanotechnology

Background:

• Dangling bonds (DBs) on H-terminated Si(100) surfaces are crucial for atomic-scale device research.
• Characterizing DBs on low-conductivity silicon substrates with scanning tunneling microscopy (STM) is challenging due to carrier screening and long mean-free paths.

Purpose of the Study:

• To investigate the effects of minority carrier (hole) injection on dangling bonds (DBs) on H-terminated Si(100) surfaces using two-probe STM.
• To explore methods for overcoming measurement challenges on low-conductivity silicon substrates for atomic-scale device characterization.

Main Methods:

• Utilized a two-probe scanning tunneling microscope (STM) setup.
• One probe performed surface characterization, while a second probe injected minority carriers (holes) into the n-type Si substrate.
• Analyzed the impact of hole injection on DB charge states and STM imaging characteristics.

Main Results:

• Injected holes migrated to negate band bending in STM imaging areas, achieving a steady state.
• The average charge states of DBs were controllable by varying the amount of injected holes.
• Hole injection induced shifts in STM apparent imaging bias and revealed additional gap states in I-V measurements for DB islands.

Conclusions:

• Minority carrier injection is an effective strategy for controlling DBs and overcoming measurement limitations on low-conductivity silicon.
• These findings provide critical insights for the development and understanding of atomic-scale devices fabricated on such substrates.