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Title: Cold atomic beam ion source for focused ion beam applications

We report measurements and modeling of an ion source that is based on ionization of a laser-cooled atomic beam. We show a high brightness and a low energy spread, suitable for use in next-generation, high-resolution focused ion beam systems. Our measurements of total ion current as a function of ionization conditions support an analytical model that also predicts the cross-sectional current density and spatial distribution of ions created in the source. The model predicts a peak brightness of 2 × 10{sup 7} A m{sup −2} sr{sup −1} eV{sup −1} and an energy spread less than 0.34 eV. The model is also combined with Monte-Carlo simulations of the inter-ion Coulomb forces to show that the source can be operated at several picoamperes with a brightness above 1 × 10{sup 7} A m{sup −2} sr{sup −1} eV{sup −1}. We estimate that when combined with a conventional ion focusing column, an ion source with these properties could focus a 1 pA beam into a spot smaller than 1 nm. A total current greater than 5 nA was measured in a lower-brightness configuration of the ion source, demonstrating the possibility of a high current mode of operation.
Authors:
;  [1] ;  [2] ;  [2] ;  [1]
  1. Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
22218259
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 114; Journal Issue: 4; Other Information: (c) 2013 © 2013 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ATOMIC BEAMS; BRIGHTNESS; COMPUTERIZED SIMULATION; CURRENT DENSITY; EV RANGE; ION BEAMS; ION SOURCES; LASERS; MONTE CARLO METHOD; PEAKS; SPATIAL DISTRIBUTION