Platinum-related defects in silicon observed by optical absorption measurements

Abstract

We investigated platinum (Pt)-related defects in silicon (Si) based on the measurement of their optical absorption and found optical absorption peaks related to Pt clusters. Pt and H were separately doped in FZ–Si by heating at 1000–1300 °C followed by quenching in water. Optical absorption spectra were measured at about 5 K with a Fourier transform infrared spectrometer. In a specimen doped with a higher concentration of H than of Pt, we observed optical absorption peaks due to four types of Pt–H complexes. In specimens with a higher concentration of Pt than of H, peaks were observed in the region from 1300 to 1700 cm−1. Based on the peak shift due to the hydrogen isotope and the dependence on excitation energy and the annealing behavior, these peaks are thought to be due to the electronic transitions of Pt-related defects such as Pt clusters, rather than the local vibrational modes of H. The defect centers which gave rise to optical absorption at about 1301, 1318, 1452, and 1474 cm−1 were IR-active centers under illumination and the optical threshold energy was determined to be about 0.34 eV by applying Lucovsky’s model [Solid State Commun. 3, 299 (1965)].