Ultraviolet light emission from si in a scanning tunneling microscope

Area of Science:

• Solid-state physics
• Materials science
• Surface science

Background:

• Scanning tunneling microscopy (STM) is a powerful tool for surface analysis.
• Luminescence phenomena in semiconductors can provide insights into electronic properties.
• Silicon (Si) is a fundamental material in semiconductor technology.

Purpose of the Study:

• To investigate ultraviolet and visible radiation emitted from Si(100) and (111) wafers during STM measurements.
• To understand the mechanisms responsible for luminescence in silicon under STM conditions.
• To analyze the spectral characteristics of the emitted radiation.

Main Methods:

• Utilizing a scanning tunneling microscope to probe Si(100) and (111) wafers.
• Applying positive and negative biases to n- and p-type silicon samples.
• Measuring the emitted ultraviolet and visible spectra.

Main Results:

• Observed ultraviolet and visible luminescence from silicon wafers in contact with STM tip.
• Identified hot electrons in silicon as the source of luminescence.
• Demonstrated electron injection from the tip and Zener tunneling as supply mechanisms.
• Spectra showed contributions from direct optical transitions in the silicon bulk.
• Confirmed hole injection from the tip and Auger processes as contributing factors.

Conclusions:

• STM-induced luminescence in silicon is primarily driven by hot electrons.
• Both electron injection and Zener tunneling play crucial roles in generating luminescence.
• Direct optical transitions in silicon bulk contribute to the observed spectra.
• The study provides a deeper understanding of electronic and optical processes at semiconductor surfaces under STM.