The relationship between hydrogen and paramagnetic defects in thin film silicon irradiated with 2 MeV electrons

Abstract

After irradiation of hydrogenated amorphous and microcrystalline silicon (a-Si:H and μc-Si:H) with 2 MeV electrons at 100 K, we observe satellite-like components close to the dominating electron spin resonance (ESR) signal of these materials. The satellites overlap with the commonly observed dangling bond resonance and are proposed to originate from a hyperfine interaction with the nuclear magnetic moment of hydrogen atoms in a-Si:H and μc-Si:H. Our present study is focused on the verification of this hypothesis. Equivalent hydrogenated and deuterated a-/μc-Si:H/D materials have been investigated with ESR before and after 2 MeV electron bombardment. From the difference between ESR spectra of hydrogenated and deuterated samples we identify the doublet structure in the ESR spectra as a hyperfine pattern of hydrogen-related paramagnetic centers. The observations of H-related paramagnetic centers in a-/μc-Si:H are of particular interest in view of metastability models of a-Si:H, which include H-related complexes as precursors for the stabilization of the metastable Si dangling bonds. The nature of the observed center is discussed in the light of known H-related complexes in crystalline Si and suggested H-related dangling bonds in a-Si:H.

Origins of hole traps in hydrogenated nanocrystalline and amorphous silicon revealed through machine learning

“…A similar theory has been put forth by Morigaki [45], in which the Si-H-Si structures are described as hydrogen-related dangling bonds in which the hydrogen atom is preferentially bound to one silicon atom. This model has been challenged by electron-spin-resonance studies indicating that there are no hydrogen atoms within 3Å of dangling bonds in a-Si:H [46,47], but more recent studies have called this conclusion into question [48][49][50]. About 2% of the structures in our sample, and three of the eight deepest hole traps, contain bridge bonds in which the difference between the two H-Si bond lengths is less than 0.05Å.…”

Electron paramagnetic resonance calculations for hydrogenated Si surfaces

“…2.008 and a H-related doublet around 2.0045. Both signals can also be observed in μc Si:H material [10]. Here, two further resonances are observed atḡ = 2.0043 andḡ = 2.0052 [11].…”

“…However, with angular average values above 2.006, this type of dangling bond cannot explain the dominant signals at 2.0043 and 2.0052. Instead, it provides an explanation for the less intense signals with large g strain between 2.006 and 2.008, which can be observed in μc Si and a-Si:H [10]. It is also reminiscent for single dangling-bond defects in silicon bulk material [29,30].…”

“…g tensor calculations via the spin currents entering Eqs. (5) and (10) are based on linear magnetic response theory. Thereby both the influence of the magnetic field B and the spinorbit coupling are considered small perturbations.…”

DNP-NMR of surface hydrogen on silicon microparticles

“…Silicon particles are known to contain localized unpaired electrons at the interface between the silicon and the silicon-oxide layers. [44,45,46,30,47,48,49] At room temperature these Si−H and Si−OH species are able to move around the surface to adjacent unoccupied dangling bonds, if any. These systems also exhibit a significant degree of heterogeneity based on the conditions under which the host materials were grown, the methods by which the powders were prepared and sorted, and the storage conditions.…”