Structure and vibrational properties ofN−H2complexes in GaAs:N

Abstract

Considerable attention has been focused on GaAs:N since it was discovered that the addition of nitrogen to gallium arsenide leads to a surprisingly large reduction in its band gap and changes in its electronic properties. Equally surprising was the discovery that subsequent hydrogenation largely negates these effects, generating a material whose properties are similar to those of GaAs. Infrared studies of the hydrogenated defect indicate that it contains two hydrogen atoms. Despite the efforts that have been made to understand these effects, there is to date no satisfactory model for the structure of the pertinent nitrogen-dihydrogen defect. We have investigated theoretically several possible models for this defect and suggest that a strong candidate is a nitrogendihydrogen complex of C 1h symmetry in which the two hydrogens are in specific inequivalent locations. Ab initio calculations using CRYSTAL2003 predict that this structure is indeed metastable, and while some issues remain unresolved, the relative magnitudes of the resulting force constants are consistent with those required in mass-and-spring models to fit experimental vibrational data.

H‐ and D‐related mid‐infrared absorption bands in Ga1–yIny As1–xNx epitaxial layers

“…The absence of the 2217 cm -1 band in some samples where the three other bands related to one specific N-D complex are present [14], challenges the model of the H-N-H center proposed recently [11,12]. The sites of the two H atoms in this model, say H A and H B , are inequivalent due to a slight rotation of the H A -N-H B complex around the vertical [110] direction, causing two different H-Ga stretching frequencies.…”

“…The calculations of Fowler et al [11] and Du et al [12] showed that a canted H-N-H complex could provide an explanation for two high-frequency but slightly different stretching modes of H(D), as experimentally observed. The symmetry of this complex is C 1h , but the deviation from the symmetrical C 2v configuration, as first discussed by Amore Bonapasta et al [19], is only small.…”

“…This discrepancy between experimental results and theoretical predictions caused further calculational investigations. The outcome was that it is possible to assign the vibrational modes to an H-N-H complex where both H atoms are bonded to N, however, in slightly different geometry [11,12]. Therefore the H atoms are inequivalent and give rise to two different stretching frequencies.…”

Microscopic origin of compressive strain in hydrogen-irradiated dilute GaAs1−yNyalloys: Role of N-HLei1, Stavola2, Fowler3 et al. 2012Phys. Rev. B150190View full textAdd to dashboardCite

“…1) eliminates the band gap shift caused by N and explains the experimentally observed vibrational properties of the deuterated alloy. [10][11][12][13] (The deuterated D-N-D defect is more easily studied by vibrational spectroscopy than the corresponding H-N-H center and is the focus of this paper.) The results of x-ray absorption near-edge spectroscopy (XANES) experiments and their interpretation have also been found to be consistent with a D-N-D complex.…”

Zero-phonon lines of nitrogen-cluster states in GaNxAs1−x: H identified by time-resolved photoluminescence

“…These materials show a very strong band gap bowing with increasing nitrogen concentration [2,3]. Post-growth annealing of these dilute nitrides induces a noticeable blue-shift of the band-gap [1], while post-growth hydrogenation effectively passivates the incorporated nitrogen atoms due to the formation of various N-H complexes [4,5].…”