Optical absorption in amorphous InN thin films

Khoshman, Jebreel M.; Kordesch, Martin E.

doi:10.1016/j.jnoncrysol.2006.09.011

Cited by 21 publications

(11 citation statements)

References 21 publications

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“…There is some work about RF sputtered InN thin films [1][2][3][4][5][6][7][8]. For example, InN was fabricated by RF sputtering and it was then oxidized to fabricate heterojunction solar cells with Si [1].…”

Section: Introductionmentioning

confidence: 99%

The properties of direct current sputtering deposited InN thin films under different gas flow rates

Cai¹,

Ye²,

Hao³

et al. 2009

Journal of Alloys and Compounds

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Section: Introductionmentioning

confidence: 99%

The properties of direct current sputtering deposited InN thin films under different gas flow rates

Cai¹,

Ye²,

Hao³

et al. 2009

Journal of Alloys and Compounds

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“…11 For amorphous InN ͑a-InN͒, a large optical gap around 1.7eV was measured in 2006. 12 However, no further experiments have been performed. No theoretical work has appeared on a-InN.…”

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confidence: 99%

Ab initiomodels of amorphous InN

Cai

Drabold

2009

Phys. Rev. B

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In this paper, we present the first structural model of amorphous indium nitride obtained from first-principles simulation. We created a small 64-atom model by quenching from the melt and analyzed a chemically ordered 250-atom model of Mousseau and Barkema. We find that both N and In atoms tend to be fourfold. Upon relaxation, we find no homopolar bonds in the small cell and only one in the 250-atom cell. The topology of the models is analyzed with pair-correlation functions, bond angle distributions, and ring statistics. The vibrational and electronic properties are also obtained. We found that density-functional methods in the local-density approximation predict a very small gap for amorphous InN, similar to the case for crystalline InN.Amorphous materials and glasses play ever more important roles in technology. Due to photovoltaic, infrared detection and imaging applications, optoelectronic devices, and potential utility for next generation flash memory devices, the physics of amorphous semiconductors has drawn renewed interest. Since most properties of amorphous semiconductors are determined by topology, the beginning of any such study is the creation of experimentally credible structural model. A material of considerable current interest is the narrow gap semiconductor InN. Also, since GaN is an established wide-gap material, it is appealing to consider InGaN alloys for photovoltaic and other applications. Studies in this direction 1 would benefit from basic information about amorphous InN ͑a-InN͒. These materials might possess a continuously variable range of optical gaps to optimize absorption of the solar spectrum. 2 There has been controversy over the band gap of zincblende crystalline-InN ͑c-InN͒ both in experimental and theoretical works. In experiment, a narrow band gap of 0.7 eV ͑Ref. 3 and 4͒ was reported, which contrasts with previous values near 1.89 eV. 5 Subsequently, these small gaps have been confirmed by additional experiments. 6-8 In theoretical work, calculations based on density-functional theory within the local-density approximation ͑LDA͒ always yield a tiny or even negative gap. 9 Methods using self-interaction and relaxation corrected pseudopotentials ͑SIRC͒ report a large gap around 1.3eV, 10 but semiempirical LDA methods show a gap around 0.85eV. 11 For amorphous InN ͑a-InN͒, a large optical gap around 1.7eV was measured in 2006. 12 However, no further experiments have been performed. No theoretical work has appeared on a-InN.In this paper, we present atomic models of amorphous InN obtained from ab initio molecular dynamics based on plane-wave LDA. The structural, dynamical, and electronic properties are discussed. To our knowledge, there is neither theoretical nor experimental work on structural properties or vibrational modes. After creating small but reasonable models of a-InN, we predict the vibrational spectrum and electronic properties. We particularly seek to connect the electronic structure to the topology of the network to better comprehend electronic and optical experiment...

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“…The band gap energy E g derived in a standard way [31,43,44] from the optical transmittance and reflectance ) 1/m vs. photon energy hν, where α is the absorption coefficient, as a point at which α=0. The power coefficient m takes a value of 1/2 for direct allowed and m=2 for indirect allowed optical transitions.…”

Section: Resultsmentioning

confidence: 99%

Study of N-doped TiO₂ thin films for photoelectrochemical hydrogen generation from water

et al. 2015

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Abstract:The present work deals with nitrogen-doped stoichiometric TiO 2 :N and non-stoichiometric TiO 2−x :N thin films deposited by means of dc-pulsed reactive sputtering for application as photoanodes for hydrogen generation from water, using solar energy. Stoichiometric thin films of TiO 2 crystallize as a mixture of anatase and rutile while rutile phase predominates in TiO 2 :N at higher nitrogen flow rates as shown by X-ray diffraction at grazing incidence, XRD GID. Lack of bulk nitridation of stoichiometric TiO 2 :N is indicated by valence-to-core X-ray emission spectroscopy, XES, analysis. The energy band gap as well as flat band potential remain almost unaffected by increasing nitrogen flow rate in this case. In contrast to that, non-stoichiometric thin films of TiO 2-x :N demonstrate systematic evolution of the structural, morphological, optical and photolectrochemical properties upon increasing level of nitrogen doping. Pronounced changes in the growth pattern of non-stoichiometric TiO 2-x :N upon varied nitrogen flow rate, demonstrated by scanning electron microscopy, SEM, can be easily correlated with the crystallographic properties studied by XRD GID. Relative positions of Kβ'' XES lines of the TiO 2-x :N thin films, which depend strongly on the nature of the ligands and their local coordination, change with the increasing nitrogen flow. Doping of nonstoichiometric titanium dioxide with nitrogen shifts the absorption spectrum towards the visible range and increases considerably the flat band potential which is beneficial for water photolysis.

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Optical absorption in amorphous InN thin films

Cited by 21 publications

References 21 publications

The properties of direct current sputtering deposited InN thin films under different gas flow rates

The properties of direct current sputtering deposited InN thin films under different gas flow rates

Ab initiomodels of amorphous InN

Study of N-doped TiO₂ thin films for photoelectrochemical hydrogen generation from water

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Optical absorption in amorphous InN thin films

Cited by 21 publications

References 21 publications

The properties of direct current sputtering deposited InN thin films under different gas flow rates

The properties of direct current sputtering deposited InN thin films under different gas flow rates

Ab initiomodels of amorphous InN

Study of N-doped TiO2 thin films for photoelectrochemical hydrogen generation from water

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Product

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Study of N-doped TiO₂ thin films for photoelectrochemical hydrogen generation from water