Negative ion production by surface ionization at aluminum-nitride surfaces

In this article, we report on the observation of the formation of negativel y charged ions upon reflection from an aluminum-nitride surface. Positive H -2 and O-2 ions are scattered at small angles of incidence off a single-cry stal surface. Charge exchange at the surface yields neutral particles and n egative ions in the reflected particle flux. The negative ion fractions are about 15% and 1% for oxygen and hydrogen, respectively. The particle refle ction probability is only 2%, which is attributed to the roughness of the s urface. (C) 2000 American Institute of Physics. [S0021-8979(00)08805-8].