Multipurpose 14.5 GHz ECR ion source. Specialities and application for surface modification

Full text: A 14.5 GHz electron cyclotron resonance ion source (ECR, ECRIS) operates in ATOMKI as a multi-purpose stand-alone device for atomic and plasma physics experiments. The ECRIS was designed to produce multiply and highly charged heavy ions, but it is able to produce low and highly charged plasmas and can deliver ion beams in wide charge and energy ranges (Q = 1-27 charge and U 0.5-30 KV extraction voltage). Besides the fundamental plasma investigations this ECR provides possibilities for versatile surface modification and etching experiments. Hillock-like nanodefects were formed on the surface of selected amorphous and crystalline chalcogenide semiconductors due to the highly charged Xe ion bombardment. The peculiarity of used semiconductors consists in the presence of covalent and van der Waals interatomic bonds, which make the structure more 'soft' in comparison with usually investigated Si, GaAs crystals and promotes stimulated reversible and irreversible structural transformations [1]. The metastability of the ion-impact excited atomic clusters in such materials more easily results in defect formation and local phase transitions, which in turn may determine the effective volume expansion, hillock formation as well as layer by layer desorption of surface atoms. We have realized the process with Xe20+ and Xe24+ and got 1-5 nm high hillocks with lateral dimensions in 50-100 nm range. Besides the fundamental aspects of localized structural transformation in solids, caused by a complex electron-hole and defect assisted process (including the kinetically assisted potential sputtering [2]) these experiments relates the problem of soft surface etching and creating nanostructures for functional electronics