Electron paramagnetic resonance versus spin-dependent recombination: Excited triplet states of structural defects in irradiated silicon

Upon illumination some structural defects in irradiated silicon can be excited into the metastable triplet S=1 states. These triplet states can be involved in the excess-carriers recombination process. This paper provides a theoretical treatment of spin-dependent recombination (SDR) via an excited triplet state and reports on the properties of its electron-paramagnetic-resonance (EPR) spectrum detected by means of dc and microwave photoconductivity changes under magnetic-resonance conditions. The dependence of the spectral lines intensity on various experimental parameters (microwave power and phase, size of the sample) has been investigated and a comparison between the two techniques and the conventional EPR method has been made. Using the SDR technique the angular dependence of the line positions and intensities for the structural defects in their excited triplet states was studied and the spin-Hamiltonian parameters of the Si-PT1 and Si-PT4 spectra have been determined.