PERFORMANCE OF MASS-ANALYZED, LOW-ENERGY, DUAL-ION BEAM SYSTEM FOR MATERIALS RESEARCH

Mass analyzed low-energy ion beams delivered into a UHV growth chamber have enormous potential for novel materials studies. However, there a re significant practical problems in the production of useful ion flux es at energies down to a few electron volts. Many of these problems ha ve been investigated during the testing of a unique new instrument. Th is instrument consists of a dual source, mass analyzed, low-energy, io n beam system attached to an ultrahigh-vacuum (UHV) deposition chamber which houses equipment for in situ Auger electron spectroscopy and re flection high-energy electron diffraction analysis of the deposited ma terial. A second UHV chamber, connected to the deposition chamber by m eans of a vacuum lock and sample transfer device, houses equipment for in situ low-energy electron diffraction and time-of-flight scattering and recoiling spectrometry. The instrument is briefly described herei n and data are presented to illustrate the effects of various paramete rs on the performance of the ion beam. The parameters considered are b eam line pressure, field penetration, electromagnetic fringing fields, retarding lens con figuration, and ion arrival energy at the target ( from 5 eV to 10 keV). The effects of these parameters on the energy sp read and profile of the beam, ion-beam flux on target for various spec ies, high-energy neutral atom content and electron content of the beam , and target chamber pressure are discussed. Examples showing the util ization of the instrument for (1) synthesis of the metastable binary c ompound carbon nitride, (2) deposition of ultrathin Al/Si multilayers, and (3) studying the growth mechanism of Si thin films, are presented . The prospects for materials research, film deposition, surface modif ication, and ion/surface chemistry studies using such an instrument ar e assessed.