Electron Paramagnetic Resonance of Boron Acceptors in Isotopically Purified Silicon

TL;DR

This study demonstrates that isotopic purification of silicon significantly narrows EPR linewidths of boron acceptors and reveals substructures due to complex spin interactions, enhancing understanding of spin dynamics in purified silicon.

Contribution

It provides the first detailed analysis of EPR linewidth reduction and substructure emergence in boron-doped isotopically purified silicon, supported by a developed spin population model.

Findings

EPR linewidths are dramatically reduced in isotopically purified 28Si.

Substructures in EPR spectra are observed, indicating complex spin interactions.

A spin population model qualitatively explains the experimental observations.

Abstract

The electron paramagnetic resonance (EPR) linewidths of B acceptors in Si are found to reduce dramatically in isotopically purified 28Si single crystals. Moreover, extremely narrow substructures in the EPR spectra are visible corresponding to either an enhancement or a reduction of the absorbed microwave on resonance. The origin of the substructures is attributed to a combination of simultaneous double excitation and spin relaxation in the four level spin system of the acceptors. A spin population model is developed which qualitatively describes the experimental results.