Scattered and recoiled ion fractions from LiTaO3(100) surfaces with different electrical properties

Time-of-flight scattering and recoiling spectrometry (TOF-SARS) was used to investigate the scattered and recoiled ion fractions from 3 keV Ar+ ion be ams on LiTaO3(100) single crystals. The TOF-SARS measurements were found to be sensitive to the electrical properties of the crystal. ac impedance mea surements of the electrical conductivity showed that LiTaO3 is an insulator at room temperature and that its conductivity increases by similar to 10(3 ) at temperatures in the range 100-200 degrees C. This increase in conducti vity could be monitored in TOF-SARS by measuring the current through the cr ystal induced by the impinging Ar+ ions as a function of temperature. The a ctivation energy for this transition was estimated from both the impedance and scattering measurements to be similar to 1 eV. Azimuthal anisotropy of the scattered Ar+ ions from Ta atoms was observed at room temperature but n ot at elevated temperatures. Scattered Ar+ ion fraction measurements showed that scattered Ar+ ions are enhanced by charge buildup on the LiTaO3 surfa ce, whereas recoiled ions are not affected. The effects of surface charging phenomena on TOF-SARS could be eliminated by either heating the LiTaO3 cry stal to similar to 200 degrees C or by application of a low energy electron beam to the crystal surface. (C) 1999 American Institute of Physics. [S002 1-9606(99)70230-8].