Atomic processes on ion-bombarded surface

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1.Experiment with high energy ion beamSecondary electrons and ions were energy analyzed as a function of surface-oxygen coverage under ion beam bombardment of Al, Mo, Ti surfaces. Basic analysis and discussions were made in detail. Secondary electrons were energy analyzed with a hand-made half sphere analyzer which is an integration type with respect to scattered angles. The yield of secondary electrons and change in the work function were measured as a function of surface-oxygen coverage. Secondary ions were measured with a time of flight type mass analyzer. It was found that the change of surface electronic state due to oxygen adsorption plays a fundamental role in emission processes of these secondary particles.2.Experiment with highly charged ionsInteraction between highly charged ions and solid surfaces were investigated under the condition of grazing incidence in order to pick up the detail of so called potential sputtering. Secondary ions emitted from a surface were mass analyzed with a time of flight mass analyzer in coincidence with scattered neutralized projectiles. The three dimensional momentum distribution of fragment ions was measured with a position sensitive detector coupled with a TOF analyzer. A cubic-GaN made by a method of halogen transport atomic layer epitaxy was investigated to have information on surface polarity. It was found that the mass spectra differ clearly between the (0001) and (0001) surfaces. The kinetic energy distribution of H^+ produced from adsorbed hydrocarbon molecules also widely differs for two surface directions. It was concluded that the surface polarity can be effectively checked with the present experimental setup using highly charged ions.