Structural and electronic properties of amorphous and polycrystalline In2Se3 films

Chaiken, A.; Nauka, K.; Gibson, Gary A. P.; Lee, Heon; Yang, Cheol‐Woong; Wu, Junqiao; Ager, Joel W.; Yu, K. M.; Walukiewicz, W.

doi:10.1063/1.1592631

Cited by 50 publications

(43 citation statements)

References 31 publications

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“…This might be crucial for explaining the discrepancies between the transport properties of a-In x Se y with different compositions. 32,33 The coordination numbers predicted in our study seem to be in good agreement with other available data in the literature. The coordination numbers of indium and selenium for a-InSe with 5.4 and 5.8 g / cm 3 density are Z In = 3.5 and 3.8; and Z Se = 2.7 and 2.9, whereas these data for a-In 0.5 Se 0.5 ͑ = 5.62 g / cm 3 ͒ 14 were claimed to be equal to four and three for indium and selenium, respectively.…”

Section: B Coordination Numbersupporting

confidence: 91%

ModelingIn−Seamorphous alloys

et al. 2005

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The structure of amorphous In x Se y ͑a-In x Se y ͒ alloys has been studied by a first principles tight-binding molecular dynamics technique. The three-dimensional amorphous structures with different densities at different compositions were prepared by quick quenching from the liquid phase. The characteristics of short-range order, namely radial distribution functions, coordination numbers, bond angle distribution functions, and the electronic structure have been analyzed. The local bonding environments of different In x Se y crystals ͑in particular, In 2 Se 3 , InSe, and In 4 Se 3 ͒ were found to be present in the amorphous phase. The average coordination number of indium is mainly four, whereas selenium is mostly two-or threefold coordinated. The majority of the bonds are heteropolar, but homopolar bonds are also present in a-In x Se y so that they cannot be excluded from a realistic description of the amorphous structure. Larger content of indium in a-In x Se y leads to an increased number of In-In bonds, as expected.

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Section: B Coordination Numbersupporting

confidence: 91%

ModelingIn−Seamorphous alloys

et al. 2005

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“…6 Depending upon the optical band gap of the film, it can be used as a window layer 7 ͑CIS/ In 2 Se 3 ͒ or absorber layer 4,8 ͑CdS / In 2 Se 3 ͒ in solar cells. 9 However, variation of thickness and annealing temperature can affect other properties of the film such as sheet resistance, [9][10][11] which can increase several orders. 7 They reduced the thickness of the In 2 Se 3 film from 1 m to ϳ 70 nm, to increase the band gap from 1.75 to 3 eV, to use it as a window layer.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of band gap and photoconductivity in gamma indium selenide due to swift heavy ion irradiation

Sreekumar

Jayakrishnan

Kartha

et al. 2008

Journal of Applied Physics

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Enhanced radiation tolerance in nitride multilayered nanofilms with small period-thicknesses Appl. Phys. Lett. 101, 153117 (2012) Strain controlled systematic variation of metal-insulator transition in epitaxial NdNiO3 thin films J. Appl. Phys. 112, 073718 (2012) Kinetics of color center formation in silica irradiated with swift heavy ions: Thresholding and formation efficiency Appl. Phys. Lett. 101, 154103 (2012) Fabricating high-density magnetic storage elements by low-dose ion beam irradiation Appl. Phys. Lett. 101, 112406 (2012) Determination of ion track radii in amorphous matrices via formation of nano-clusters by ion-beam irradiation ␥-In 2 Se 3 thin films prepared at different annealing temperatures ranging from 100 to 400°C were irradiated using 90 MeV Si ions with a fluence of 2 ϫ 10 13 ions/ cm 2 . X-ray diffraction analysis proved that there is no considerable variation in structural properties of the films due to the swift heavy ion irradiation. However, photosensitivity and sheet resistance of the samples increased due to irradiation. It was observed that the sample, which had negative photoconductivity, exhibited positive photoconductivity, after irradiation. The negative photoconductivity was due to the combined effect of trapping of photoexcited electrons, at traps 1.42 and 1.26 eV, above the valence band along with destruction of the minority carriers, created during illumination, through recombination. Photoluminescence study revealed that the emission was due to the transition to a recombination center, which was 180 meV above the valence band. Optical absorption study proved that the defects present at 1.42 and 1.26 eV were annealed out by the ion beam irradiation. This allowed photoexcited carriers to reach conduction band, which resulted in positive photoconductivity. Optical absorption study also revealed that the band gap of the material could be increased by ion beam irradiation. The sample prepared at 400°C had a band gap of 2 eV and this increased to 2.8 eV, after irradiation. The increase in optical band gap was attributed to the annihilation of localized defect bands, near the conduction and valence band edges, on irradiation. Thus, by ion beam irradiation, one could enhance photosensitivity as well as the optical band gap of ␥-In 2 Se 3 , making the material suitable for applications such as window layer in solar cells.

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“…Indium selenide is an n-type semiconductor with a optimum direct-band gap, efficient visible-light absorption and phase-change memorized effect [10,11], which have been closely related to its nanocrystals uses such as photodetectors [12,13], optical filters [14], solar cell devices [15][16][17], random access memories [18,19], photocatalysts for H 2 production from water [20]. Owing to the mismatch of valence electron numbers, indium selenide compounds often show several valency-changed structures with different stoichiometries.…”

Section: Introductionmentioning

confidence: 99%