The structure of amorphous Si and Ge

Rudee, M. L.; Howie, A.

doi:10.1080/14786437208229319

Cited by 141 publications

(34 citation statements)

References 20 publications

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“…Coherent scattering regions approximately 15 A or smaller in size have been observed in dark field microscopy. Based on these observations, Rudee and Howie [9] have suggested a microcrystallite model in which the structure is hexagonal wurtzite rather than diamond cubic. These authors also show that the reduced intensity function calculated on the basis of a wurtzite structure fits over a considerable range of the experimental data on silicon obtained by MOSS and Graczyk [ll].…”

Section: Introductionmentioning

confidence: 92%

A Scanning Electron Diffraction Study of Vapor‐Deposited and Ion Implanted Thin Films of Ge (I)

Graczyk

Chaudhari

1973

Physica Status Solidi (b)

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The structure of Ge films evaporated by several methods onto room temperature substrates of NaCl and films which have been ion implanted with 3 x 1015, 30 to 40 keV Ge74 has been investigated via a scanning electron diffraction instrument with electron energy filtering. The radial distribution functions of all fil-ms are very similar and exhibit strong correlation peaks a t 2.45, 4.00, and (4.85 f 0.075) A with coordinations of 4,12, and = 7, respectively. The remaining major peaks for higher r deviate substantially from the diamond cubic form of Ge. From the RDF analysis a density ratio ~o /~c r y s t of 0.86 to 0.95 is determined. Thermal anneal experiments showed that the films may be annealed to a density of -0.97 of crystalline density without crystallization. Amorphous films which have been ion implanted with the same energy and dose as the polycrystalline films show a considerable concentration of pores and voids of a maximum diameter of 100 A. The RDF, however, is identical to the as-deposited film with the exception of some changes in the correlation for r greater than 11 A.Die Struktur dunner Ge-Schichten, die auf verschiedene Arten auf NaC1-Triiger bei

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Section: Introductionmentioning

confidence: 92%

A Scanning Electron Diffraction Study of Vapor‐Deposited and Ion Implanted Thin Films of Ge (I)

Graczyk

Chaudhari

1973

Physica Status Solidi (b)

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“…Our PC model is similar to the earlier microcrystalline model. 20 However, this earlier model failed to reproduce the diffraction spectrum, 21 which can be attributed to the lack of elastic deformation of the small crystalline grains. The atomistic computational techniques used to generate the PC model structures include the effects of strain, and thus provide structures that can appear amorphous to diffraction but also be topologically crystalline, provided the grains are small enough ͑Ͻ30 Å͒.…”

Section: Introductionmentioning

confidence: 99%

Structure and physical properties of paracrystalline atomistic models of amorphous silicon

Voyles

Zotov

Nakhmanson

et al. 2001

Journal of Applied Physics

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We have examined the structure and physical properties of paracrystalline molecular dynamics models of amorphous silicon. Simulations from these models show qualitative agreement with the results of recent mesoscale fluctuation electron microscopy experiments on amorphous silicon and germanium. Such agreement is not found in simulations from continuous random network models. The paracrystalline models consist of topologically crystalline grains which are strongly strained and a disordered matrix between them. We present extensive structural and topological characterization of the medium range order present in the paracrystalline models and examine their physical properties, such as the vibrational density of states, Raman spectra, and electron density of states. We show by direct simulation that the ratio of the transverse acoustic mode to transverse optical mode intensities I TA /I TO in the vibrational density of states and the Raman spectrum can provide a measure of medium range order. In general, we conclude that the current paracrystalline models are a good qualitative representation of the paracrystalline structures observed in the experiment and thus provide guidelines toward understanding structure and properties of medium-range-ordered structures of amorphous semiconductors as well as other amorphous materials.

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“…Rudee and Howie [32] investigated sputtered Ge using HREM and found it to have a microcrystalline structure rather than an amorphous one. They found excellent agreement between the experimental diffraction patterns of the sputtered Ge and those calculated from dh Ge.…”

Section: Hexagonal Gennaniummentioning

confidence: 99%