Role of surface composition in morphological evolution of GaAs nano-dots with low-energy ion irradiation

Abstract

The surface chemistry of GaAs (100) with 50-keV Ar+ ion beam irradiation at off-normal incidence has been investigated in order to elucidate the surface nano-structuring mechanism(s). Core level and valence band studies of the surface composition were carried out as a function of fluences, which varied from 1 × 1017 to 7 × 1017 ions/cm2. Core-level spectra of samples analyzed by X-ray photoelectron spectroscopy confirmed the Ga enrichment of the surface resulting in bigger sized nano-dots. Formation of such nano-dots is attributed to be due to the interplay between preferential sputtering and surface diffusion processes. Valence band measurement shows that the shift in the Fermi edge is higher for Ga- rich, bigger sized nano-dots due to the partial oxide formation of Ga. ‘One-dimensional power spectral density’ extracted from atomic force micrographs also confirms the significant role of surface diffusion in observed nano-structuring.

Surface Reconstruction, Oxidation Mechanism, and Stability of Cd3As2

“…Concerning As core levels, upon oxidation a downshift by 0.15 eV up to BE = 40.38 eV is observed for As‐3d 5/2 , with the appearance of another couple of Voigt doublets with the J = 5/2 component at 43.71 and 43.32 eV, respectively, due to oxidation. While these values deviate from BEs in As 2 O 3 (44.9 eV ) and As 2 O 5 (45.8 eV), the central positions of the doublets are slightly lower than those reported for As 2 O 3 and As 2 O 5 species in oxidized GaAs . Therefore, we attribute both doublets to the formation of hybrid AsOCd bonds.…”

Advantage of dual-confined plasmas over conventional and facing-target plasmas for improving transparent-conductive properties in Al doped ZnO thin films

“…The energies of these charged carriers (~tens of eV) can be estimated using the transitions observed in OES spectra. These smaller values of energies are necessary to avoid the surface structuring arisen from the nuclear energy losses as reported in ions with energy of N 10 3 eV [34][35][36][37][38]. In OES results, strong Ar radiative as well as metastable radicals are observed at 750.89 nm, 763.51 nm, and 811.53 nm corresponding to 3p 5 4p(2 p1 ) → 3p 5 4s(1 s2 ), 3p 5 4p(2 p6 ) → 3p 5 4s(1 s5 ) and 3p 5 4p(2 p9 ) → 3p 5 4s(1 s5 ) transitions respectively, similarly to earlier reported in literature [26].…”

Investigations of ripple pattern formation on Germanium surfaces using 100-keV Ar+ ions

“…In the case of a binary compound, the difference in the sputtering rates also plays a significant role in the pattern formation onto a surface due to different masses present inside the material. The lighter element will sputter more readily than the one with higher mass, as seen by different research groups for InP [4], GaAs [34], Gasb [5], etc. But for the single element material, it may be difficult to achieve the ripple formation, although there are contradictory reports on this especially for the cases of Si targets [2,10] but not so clearly visible on Ge [18].…”