Stabilization of amorphous GaN by oxygen

Budde, F.; Ruck, B. J.; Koo, Annette; Granville, S.; Trodahl, H. J.; Bittar, A.; Williams, G. V. M.; Ariza, Manuel R. Gómez; Bonnet, B.; Jones, Deborah J.; Metson, James B.; Rubanov, S.; Munroe, Paul

doi:10.1063/1.2014937

Cited by 25 publications

(27 citation statements)

References 34 publications

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“…26,27 The films grown at 500 eV were transparent across the visible region and showed an edge whose energy and structures were in close agreement with crystalline material, suggesting a low density of gap states and homopolar bonds. In addition, structural investigations were carried out on a-GaN with around 10-20% O using x-ray absorption near edge spectroscopy.…”

Section: Amorphous Gan Characterizationmentioning

confidence: 67%

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Ion Beam Analysis of Amorphous and Nanocrystalline Group III-V Nitride and ZnO Thin Films

Kennedy

Markwitz

Trodahl

et al. 2007

Journal of Elec Materi

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The ion beam analysis (IBA) techniques of Rutherford backscattering spectrometry (RBS), elastic recoil detection analysis (ERDA), nuclear reaction analysis (NRA), and particle-induced x-ray emission (PIXE) have been used to quantitatively determine composition, uniformity, impurity, and elemental depth profiles of major, minor, and trace elements of group III-V nitride and zinc oxide (ZnO) thin films prepared by various growth techniques. The IBA revealed that an amorphous GaN film prepared by ion beam assisted deposition (IBAD) has large variations in film thickness and composition coupled with typically 10-20% oxygen that was found to be essential to stabilize their amorphous structure. The IBA characterization of plasma-assisted molecular beam epitaxy (PAMBE) grown GaN, InN, and InCrN films revealed composition, impurity, and uniformity information of the films. The IBA of ZnO films prepared by radio frequency (RF) sputtering showed that the Zn/O ratio often varied significantly over the film thickness. Hydrogen was found to be a major impurity in the films with around one present in the as-deposited ZnO films. It is clearly shown that the nondestructive, quantitative, and rapid IBA measurements are very useful to develop and optimize growth protocols in respect to film thickness, stoichiometry, and especially in regard to hydrogen and oxygen impurities for group III-V nitride and ZnO thin films prepared by various growth techniques.

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Section: Amorphous Gan Characterizationmentioning

confidence: 67%

“…The GaN films prepared under UHV conditions (low oxygen) possess a nanocrystalline structure with neatly random stacked nanocrystals. 27 …”

Section: Amorphous Gan Characterizationmentioning

confidence: 97%

Ion Beam Analysis of Amorphous and Nanocrystalline Group III-V Nitride and ZnO Thin Films

Kennedy

Markwitz

Trodahl

et al. 2007

Journal of Elec Materi

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“…1(d) and (e)). Based on research by Budde et al [15] amorphous GaN can only exist in the presence of 15% or more oxygen, which generates nontetrahedral bonds centered on oxygen. The obvious lack of oxygen in our GaN nucleation layers suggests that the amorphous-like matrix can only be attributed to GaN nano-crystals that are not oriented along or close to one of the low-index directions.…”

Section: Discussionmentioning

confidence: 99%

Structural evolution of GaN layers grown on (0001) sapphire by hydride vapor phase epitaxy

Meng

Han

McFelea

et al. 2011

Journal of Crystal Growth

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“…23 -25 The presence of oxygen in GaN seems to promote the formation of Ga vacancies 22 and to stabilize the long-range amorphous structure. 25,26 We have prepared nanocrystalline and amorphous GaN films on a wide variety of substrates by ion-assisted deposition (IAD). 9 This method provides homogeneous films with a good control of the stoichiometry over a wide range of thicknesses.…”

Section: Introductionmentioning

confidence: 99%

“…Stoichiometric nanocrystalline GaN with <1 at.% of oxygen impurities have been prepared working at a base pressure of 10 8 Torr. 26 To prepare amorphous films, the water-vapour partial pressure should be increased up to 10 5 Torr, giving films containing up to 20 at.% of oxygen for deposition times of <50 min. 28 Chemical, structural and optical properties of these films have been reported already 12 -15 and the optoelectronic properties have been correlated with their nanostructure.…”

Section: Introductionmentioning

confidence: 99%

Evolution of the local structure in GaN:O thin films grown by ion‐assisted deposition with film thickness

Ariza¹,

Koo²,

Trodahl³

et al. 2005

Surface & Interface Analysis

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Optical and optoelectronic properties of gallium nitride strongly depend on the synthesis procedure, which may be related to specific structural characteristics of GaN inherent to each preparation condition. Amorphous and nanocrystalline GaN films have been prepared by ion-assisted deposition (IAD). The films prepared at 10 −5 Torr for <50 min have shown exploitable optoelectronic properties, in spite of the high concentration of oxygen of these films (up to 25 at.%). We study here the evolution of the local structure around Ga atoms as the deposition time increases. Five IAD GaN films of thickness ranging between 140 and 450 nm on silicon substrates were analysed by x-ray absorption fine structure (XAFS) at the Ga K-edge. The first and second shells of neighbouring atoms are clearly identified in the radial distribution functions at approximately 1.9 and 3.2Å, respectively. In all of the films, Ga seems to be tetrahedrally coordinated to four nitrogen atoms, some of which may be substituted by oxygen. For deposition times <50 min, analysis of both x-ray adsorption near-edge structure (XANES) and extended x-ray adsorption fine structure (EXAFS) regions indicates that the material is highly amorphous. Above this threshold, a peak corresponding to the first coordination sphere of Ga atoms becomes discernible and increases in intensity for longer deposition times, indicating that the second shell of atoms is now more ordered. The pseudo Debye-Waller factor of the Ga shell is used for monitoring the average degree of amorphization in an ∼100 nm thick top layer, which seems to be related to the film oxygen content. The XAFS results are compatible with a layered distribution of crystallinity, as has been suggested previously for these films.

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Stabilization of amorphous GaN by oxygen

Cited by 25 publications

References 34 publications

Ion Beam Analysis of Amorphous and Nanocrystalline Group III-V Nitride and ZnO Thin Films

Ion Beam Analysis of Amorphous and Nanocrystalline Group III-V Nitride and ZnO Thin Films

Structural evolution of GaN layers grown on (0001) sapphire by hydride vapor phase epitaxy

Evolution of the local structure in GaN:O thin films grown by ion‐assisted deposition with film thickness

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