Real-Time Observation of Self-Interstitial Reactions on an Atomically Smooth Silicon Surface

TL;DR

This study provides the first real-time visualization of self-interstitial reactions on atomically smooth silicon surfaces, revealing how surface-bulk defect interactions influence silicon mass flux and surface morphology at high temperatures.

Contribution

It introduces the first real-time experimental observation of self-interstitial reactions on a silicon surface, elucidating their kinetics and impact on surface morphology.

Findings

Self-interstitials are annihilated at the silicon surface, causing silicon mass flux from bulk to surface.

Surface reactions are dominated by atomic step edge interactions.

Activation energy and energy barriers for defect interactions and gold penetration are estimated.

Abstract

Self-diffusion and impurity diffusion both play crucial roles in the fabrication of semiconductor nanostructures with high surface-to-volume ratios. However, experimental studies of bulk-surface reactions of point defects in semiconductors are strongly hampered by extremely low concentrations and difficulties in the visualization of single point defects in the crystal lattice. Herein we report the first real-time experimental observation of the self-interstitial reactions on a large atomically smooth silicon surface. We show that non-equilibrium self-interstitials generated in silicon bulk during gold diffusion in the temperature range 860-1000^oC are annihilated at the (111) surface, producing the net mass flux of silicon from the bulk to the surface. The kinetics of the two-dimensional islands formed by self-interstitials are dominated by the reactions at the atomic step edges. The activation energy for the interaction of self-interstitials with the surface and energy barrier for gold penetration into the silicon bulk through the surface are estimated. These results demonstrating that surface morphology can be profoundly affected by surface-bulk reactions should have important implications for the development of nanoscale fabrication techniques.