Correlation of residual impurity concentration and acceptor electron paramagnetic resonance linewidth in isotopically engineered Si

摘要

Electron paramagnetic resonance (EPR) experiments on boron acceptors in isotopically engineered ~(28)Si samples with different degrees of chemical and isotopic purity are reported. The strong suppression of isotope-induced broadening effects in this material allows a direct observation of the linear correlation between the width of the inter-subband △m = 1 EPR line and the concentrations of carbon, oxygen, and boron point defects down to a total concentration of ≈2×10~(15) cm~(-3). When the impurity level is decreased further, the linewidth does not fall below 2.3 ± 0.2 mT, for which we discuss possible origins.