ELECTRON-PARAMAGNETIC RESONANCE IDENTIFICATION OF THE ORTHORHOMBIC IRON-INDIUM PAIR IN SILICON

A different EPR spectrum (Lu4) in silicon doped with indium and iron is reported together with an EPR spectrum previously observed by Ludwig and Woodbury. The two spectra show orthorhombic symmetry and are found to originate from the same FeIn pair. They are explained as transitions within the two Kramers doublets of an S=3/2 system with a zero-field splitting which is very large compared with the microwave energy. The ratio between the orthorhombic and axial fine-structure parameters is determined to be E/D=0.052, and the g values of the defect were found to be gz=2.09, gy=2.05, and gx=2.07(z100, and ,y 110). The temperature dependence of the intensities of both spectra shows that the lower doublet corresponds to Lu4 and the upper one to the previously observed spectrum. Contrary to what has hitherto been believed, this observation implies that the axial fine-structure parameter has the same sign for the iron-indium pair as for the iron-aluminum and iron-gallium pairs. © 1990 The American Physical Society.