Sputtering processes in AlxGa1-xAs and the effects on post-ionization detection

Resonance ionization mass spectrometry (RIMS) of neutral atoms and molecules sputtered from GaAs and AlxGa1-xAs is used to elucidate sputtering mechanisms. Sputter yields are measured for a variety of ion beam types, energies and angles of incidence. Although Xe+ sputtering may have greater yields than Ar+, thus removing more material per unit time for post-ionization detection, a significant fraction of molecules, e.g. Al2, are formed, reducing atomic signals. At low incident energy (2 keV) and high angle of incidence (60deg), Al RIMS signals are not linearly related to Al content. Possible preferential sputtering of As by Xe+ in AlAs promotes Al2 formation, thus reducing Al signals. Ar+ sputtering improves atomization efficiency. (orig.)