An ultra-low energy (30-200eV) ion-atomic beam source for ion-beam-assisted deposition in ultrahigh vacuum

Abstract

The paper describes the design and construction of an ion-atomic beam source with an optimized generation of ions for ion-beam-assisted deposition under ultrahigh vacuum (UHV) conditions. The source combines an effusion cell and an electron impact ion source and produces ion beams with ultra-low energies in the range from 30eV to 200eV. Decreasing ion beam energy to hyperthermal values (≈101eV) without loosing optimum ionization conditions has been mainly achieved by the incorporation of an ionization chamber with a grid transparent enough for electron and ion beams. In this way the energy and current density of nitrogen ion beams in the order of 101eV and 101 nAcm2, respectively, have been achieved. The source is capable of growing ultrathin layers or nanostructures at ultra-low energies with a growth rate of several MLsh. The ion-atomic beam source will be preferentially applied for the synthesis of GaN under UHV conditions. © 2011 American Institute of Physics.