Epitaxial Growth and Structure of CdSe Evaporated in Vacuum onto Ge

Gejji, F. H.; Holt, D. B.

doi:10.1149/1.2134255

Cited by 14 publications

(4 citation statements)

References 15 publications

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“…Similarly Gejji and Holt (1975) observed misorientation effects for CdSe on Ge. These authors interpreted their results in terms of a screw misfit dislocation model proposed by Matthews (1974).…”

Section: Lead a I D Tlzalliuin On (111) D U E Rmentioning

confidence: 64%

The epitaxial growth of lead and thallium on (111) silver and copper

Rawlings

Gibson

Dobson

1978

J. Phys. D: Appl. Phys.

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A combination of LEED, RHEED and AES has been used to observe lead and thallium growing in a layer-by-layer manner on (111) silver, and in the Stranski-Krastanov mode on (111) copper. Ordered sub-monolayer structures were observed for growth on the silver substrate but not for the copper substrate. However, for growth on the copper substrate a substantial contraction in the lead and thallium nearest-neighbour spacing ( approximately 3%) was observed at an approximately one monolayer coverage. It is suggested that the resulting strain in the overlayer may be responsible for the Stranski-Krastanov growth mode. Non-parallel epitaxial layers were formed by lead on silver, and by thallium on both copper and silver. The occurrence of such deposits may be linked with directional bonding forces at the interface, and/or stabilised via the existence of low-angle tilt boundaries in the overgrowth.

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Section: Lead a I D Tlzalliuin On (111) D U E Rmentioning

confidence: 64%

The epitaxial growth of lead and thallium on (111) silver and copper

Rawlings

Gibson

Dobson

1978

J. Phys. D: Appl. Phys.

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“…A vacuum evaporation technique to study the epitaxial growth and structure of CdSe evaporated onto Ge. The films were grown by Geijji and Holt (1975) and Holt and Wilcox (1971) by evaporation in a conventional, oil-pumped high vacuum system using a focused electron beam furnace. Depositions were carried out at a pressure of a few times 10 6 torr.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Cadmium Selenide Thin Film for Solar Cell Application

Alamgir

Pervaiz

Arif

2011

Energy Sources, Part A: Recovery, Utilization, and Environmenta

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Thin films of cadmium selenide were prepared by thermal evaporation. The films were grown at different substrate temperatures ranging from room temperature to 300 ı C. All the films were grown under similar conditions (i.e., the chamber pressure and source current were held constant). The films were characterized optically, electrically, and structurally. The result of optical and electrical investigation shows that these films are suitable for solar cell applications. The conductivity of the film increases with the increase in substrate temperature, hence increase in grain size. These films possess low value of resistivity, and band gap lies in the range that is suitable for the said purpose.

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“…29À38 Here, we utilize relatively unexplored IV/IIÀVI epitaxy to enhance the photoluminescence and improve the optical stability of Ge nanocrystals. 39,40 …”

mentioning

confidence: 99%

“…Although near-IR PL quantum yields as high as 8% were originally reported, these are now know believed to be much lower, and typically hover between zero (0) and below 1%. Epitaxial growth of a surface-passivating layer is a common strategy employed in the synthesis of highly luminescent II–VI, III–V and IV–VI semiconductor quantum dots. − Here, we utilize relatively unexplored IV/II–VI epitaxy to enhance the photoluminescence and improve the optical stability of Ge nanocrystals. , …”

mentioning

confidence: 99%

Near-Infrared Photoluminescence Enhancement in Ge/CdS and Ge/ZnS Core/Shell Nanocrystals: Utilizing IV/II–VI Semiconductor Epitaxy

et al. 2014

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Ge nanocrystals have a large Bohr radius and a small, size-tunable band gap that may engender direct character via strain or doping. Colloidal Ge nanocrystals are particularly interesting in the development of near-infrared materials for applications in bioimaging, telecommunications and energy conversion. Epitaxial growth of a passivating shell is a common strategy employed in the synthesis of highly luminescent II-VI, III-V and IV-VI semiconductor quantum dots. Here, we use relatively unexplored IV/II-VI epitaxy as a way to enhance the photoluminescence and improve the optical stability of colloidal Ge nanocrystals. Selected on the basis of their relatively small lattice mismatch compared with crystalline Ge, we explore the growth of epitaxial CdS and ZnS shells using the successive ion layer adsorption and reaction method. Powder X-ray diffraction and electron microscopy techniques, including energy dispersive X-ray spectroscopy and selected area electron diffraction, clearly show the controllable growth of as many as 20 epitaxial monolayers of CdS atop Ge cores. In contrast, Ge etching and/or replacement by ZnS result in relatively small Ge/ZnS nanocrystals. The presence of an epitaxial II-VI shell greatly enhances the near-infrared photoluminescence and improves the photoluminescence stability of Ge. Ge/II-VI nanocrystals are reproducibly 1-3 orders of magnitude brighter than the brightest Ge cores. Ge/4.9CdS core/shells show the highest photoluminescence quantum yield and longest radiative recombination lifetime. Thiol ligand exchange easily results in near-infrared active, watersoluble Ge/II-VI nanocrystals. We expect this synthetic IV/II-VI epitaxial approach will lead to further studies into the optoelectronic behavior and practical applications of Si and Ge-based nanomaterials. E lemental germanium (Ge) is a relatively abundant and robust covalent semiconductor. 1 Ge has a small indirect band gap (0.661 eV or 1876 nm) and a large Bohr radius (24 nm), which together theoretically provide for a wide range of emission energies attainable via size-tunable quantum confinement. 2À4 Further, recent reports suggest that strain 5À7 and doping strategies 8 may result in direct band gap Ge nanostructures. As such, Ge is particularly interesting in the development of near-infrared (near-IR) active quantum dot fluorophores for applications in biology (imaging and tracking), telecommunications, and energy conversion (photovoltaics, photocatalysis). ABSTRACT Ge nanocrystals have a large Bohr radius and a small, size-tunable band gap that may engender direct character via strain or

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Epitaxial Growth and Structure of CdSe Evaporated in Vacuum onto Ge

Cited by 14 publications

References 15 publications

The epitaxial growth of lead and thallium on (111) silver and copper

The epitaxial growth of lead and thallium on (111) silver and copper

Characterization of Cadmium Selenide Thin Film for Solar Cell Application

Near-Infrared Photoluminescence Enhancement in Ge/CdS and Ge/ZnS Core/Shell Nanocrystals: Utilizing IV/II–VI Semiconductor Epitaxy

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