Microscopic spatial fluctuations of the EL2 defect in semi-insulating GaAs: Influence on bulk resistivity and correlation with implant activation

Abstract

High-resolution EL2 topography has been compared with the electrical characteristics of the bulk material and Si-implanted layers by using resistivity and capacitance mapping. The typical cellular features are revealed in one-to-one correspondence. Microscopic variations of the bulk resistivity in the range 107<ρ<108 Ω cm can be explained quantitatively by fluctuations of the EL2 defect density and a constant carbon-acceptor concentration. A higher activation of Si is observed in regions with a higher EL2 density, leading to an estimated influence on threshold voltages of −28 mV/1015 cm−3 EL2 variation.