Photoacoustic signals from the ion-implanted layer of silicon substrate

A nonradiative transition in ion-implanted and epitaxially grown layers on Si substrate were measured by a piezoelectric photoacoustic (PA) spectroscopy. It is considered that the observed peak at 1.07 eV is caused by a nonradiative recombination of optically excited electrons from boron acceptor levels. The decrease of the 1.07 eV peak intensity by ion implantation is considered to be due to a formation of surface damaged layer with deep defect levels. The PA spectra of epitaxially grown samples are well explained by summing the spectra of p- and n-type bulk samples. The electric field at the p-n junction is not effective for the PA signal generation mechanism