Electron stimulated desorption on diamond (100) as a negative hydrogen source

The electron-stimulated desorption of negatively charged hydrogen ions from diamond surfaces is studied with respect to an application as a bright ion source. Bombarding an (100)-oriented, boron-doped single crystal diamond w ith 40-mu A electrons at energies up to 12 keV, a maximum ion current of 70 0 pA negative hydrogen is obtained. A supply of 1.0 X 10(-4) mbar atomic de uterium results in a steady-state ion current of 30 pA. The ionization cros s section has been proven to vary one order of magnitude between 3.5 x 10(- 18) cm(2) and 5 x 10(-19) cm2 with hydrogen coverage of the surface. This e ffect might be caused by the changing electron affinity of the diamond. (C) 1999 Elsevier Science B.V. All rights reserved.