X‐ray photoelectron spectroscopy of SPE‐grown bcc‐Fe, polycrystal and β‐FeSi₂ phases on Si(111) surfaces

Abstract

Ultrathin films of iron silicides were grown on Si(111) surfaces by solid phase epitaxy (SPE); iron deposition and subsequent annealing, and analyzed using in situ high energy-resolution X-ray photoelectron spectroscopy (XPS). We analyzed peaks using Lorentzian and Donaich-Šunjić curves and estimated the validity of both fittings. Under the sequence from bcc-Fe to polycrystal phase (the mixture of Fe 3 Si and β-FeSi 2 ), and then β-FeSi 2 phase with annealing process, the slight chemical shifts of Fe 2p 3/2 toward higher binding energy (BE) and the reduction of peak asymmetry for Fe 2p 3/2 and Fe 2p 1/2 were observed. We attributed this behavior to the reduction of the metallicity in iron silicide films.

Characterization of Fe Silicide Growth on Si(111) Surface by Weissenberg RHEED

“…These rods and the modulations are consistent with β-FeSi 2 on the Si(111) surface. The epitaxial orientation in the present work agrees with previous studies [2,[7][8][9][10][11][12]. The rod pattern indicate the flatness of the β-FeSi 2 (110) or β-FeSi 2 (101) film.…”

“…Sections of 3D recip- (111) is consistent with previous work by Hattori et al [11,12]. In addition to the diffuse spots from Fe(111) islands, 1 × 1 surface rods were also observed below ∼10 ML as shown in Fig.…”

“…Since Fe is the most common ferromagnetic element, it is crucial to understand how Fe interacts with Si, and how Fe grows on a Si substrate. It is known that when Fe is deposited on a Si substrate, several types of Fe silicides, such as α-FeSi 2 , β-FeSi 2 , γ-FeSi 2 , c-FeSi and -FeSi are formed on the substrate after thermal reactions [1][2][3][4][5][6][7][8][9][10][11][12]. Although most of these silicides are non-magnetic, they are important from another point-of-view.…”

“…In particular, β-FeSi 2 is a semiconductor with a low environmental load, whose band gap is suitable for optical communication devices. However, most previous studies are contradictory in terms of the growth conditions or the resulting silicide species on Si [1][2][3][4][5][6][7][8][9][10][11][12].…”

“…In order to exactly determine the silicide species, one needs to investigate the reciprocal space in three dimensions. In addition to silicides with cubic unit cells, it is also known that β-FeSi 2 (orthogonal unit cell) grows with the epitaxial orientation of (110) [7][8][9][10][11][12].…”