GENERATION OF A VELOCITY SELECTED, PULSED-SOURCE OF HYPERTHERMAL (1-10 EV) NEUTRAL METAL ATOMS FOR THIN-FILM GROWTH-STUDIES

The laser-induced vaporization by back-illumination technique is shown to generate well characterized, repetitively pulsed beams of hyperthe rmal neutral Co atoms with kinetic energies ranging from 1 to 10 eV. A t a repetition rate of 10 Hz, and a distance of 0.53 m, 2 X 10(11) Co atoms/ cm(2) per pulse are produced with less than 2 X 10(7) ions/cm(2 ) per pulse, These beams can be used as an ultrahigh vacuum deposition source for thin film growth studies. The hyperthermal beam is deposit ed on polished Si(100) wafers and particulates deposited by the beam a re detected using ex situ scanning electron microscopy. A mechanical c hopper allows tunable velocity selection of the fast neutral atoms and is shown to eliminate particulates from the beam. Line-of-sight time- of-fight quadrupole mass spectrometry is used to measure kinetic energ y distributions. Applications of the novel hyperthermal neutral atom s ource to kinetic energy enhanced neutral epitaxy are discussed. (C) 19 97 American Vacuum Society.