Impact of bombardment by Ar⁺, Na⁺ and O₂⁺ ions on spectra of elastically scattered electrons of single-crystal Ge

Abstract

The impact of bombardment by Ar+, Na+, and O2+ ions on crystal structure, composition, and excitation energy of plasma oscillations and band-to-band transitions, was studied using elastically scattered electron spectroscopy. It has been shown that, regardless of the type of ions, after bombardment with ions with E0 = 1 keV at saturation dose D = Dsat, the near-surface layers of Ge(111) were subjected to significant disorientation. While in the case of bombardment by Ar+ ions, we don’t see any noticeable change in the composition, energy of band-to-band transitions, and excitation of plasma oscillations, the bombardment by Na+ and O2+ ions appear to lead to the formation of compounds between atoms of Ge and dopant atoms. As a result, we witness a somewhat dramatic change in the structure of the spectrum of elastically scattered electrons (ESE); in particular, the spectrum changes dramatically: in the range Ep ≤ 25 − 30 eV, whereby all features pertinent to Ge(111) seem to disappear altogether whereas those formerly unknown do appear instead. After heating of Ge(111) previously implanted by Na+ ions at T = 750 K, a continuous homogeneous NaGe film with a thickness of 35−40 Å is formed, and in the case of O2+ A GeO2 film with a 20−25 Å thickness formed at T = 850 K. The share of ion bond and the charge quantity Δq transferred by cation to anion were determined judging by a chemical shift of M45 core level peak of Ge.