Small, simple and high efficiency arsenic ion source

• Published in: Vacuum Vol. 34; no. 1; pp. 251 - 257
• Main Authors: Lejeune, C, Gautherin, G
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 1984
• ISSN: 0042-207X; 1879-2715
• DOI: 10.1016/0042-207X(84)90137-4

An ion source is presented which produces a continuous, uncontaminated, high current (1–100 ωA) beam of arsenic with a high charge utilization efficiency. The main advantages of this source are related to two unique features: (1) the unmagnetized hot cathode discharge in which the primary electrons are electrostatistically trapped: (2) the design of the cylindrical oven, which is all around the 10mm dia ionization chamber and is connected to it through a pneumatic valve. The source has the following characteristics which make it suitable for application into UHV reactors: (1) small size; (2) no support gas; (3) stable and reproducible beam performances: (4) low power requirements-about 30 W for the oven, and 10 W for the discharge; (5) cathode life about 100 h, (6) low charge utilization rate, about 10 mg h −1, (7) ability to operate efficiently on either gas or solids. The basic characteristics of a 80 ωA beam accelerated to 3 kV are: composition over polyatomic ions- As + 20%, As 2 + As 3 + 10%, As 4 + 50%; axial energy spread-15 eV; divergence-5°; normalized emittance-4 × 10 −9 πrad × m; neutral ionization efficiency-7%.