Epitaxial Bi∕GaAs(111) diodes via electrodeposition

Bao, Zhi Liang; Kavanagh, K. L.

doi:10.1063/1.2161849

Cited by 19 publications

(12 citation statements)

References 13 publications

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“…Interestingly, grains rotated by 90°were not observed indicating that the Bi nucleation was sensitive to surface misorientation or step chemistries. 13 Faint triangular features are also found on the Bi film surfaces grown on GaAs ͑100͒ substrates while the Bi/ GaAs ͑110͒ substrate surfaces were relatively featureless. 19 Scanning electron microscopy ͑SEM͒ images of the Bi films deposited on GaAs ͑111͒, ͑100͒, and ͑110͒ substrates are shown in Fig.…”

Section: Resultsmentioning

confidence: 98%

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Epitaxial Bi∕GaAs diodes via electrodeposition

Bao¹,

Kavanagh²

2006

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Epitaxial Bi/ GaAs diodes have been formed by electrodeposition from bismuth nitrate and ammonium sulfate ͑͑NH 4 ͒ 2 SO 4 ͒ aqueous solutions. Bi grows ͑0001͒ oriented on both GaAs ͑111͒B and ͑001͒ substrates while it tilts 16°to a ͑011 គ 8͒ surface orientation for ͑011͒ GaAs. The metal orients in all cases with its ͕112 គ 0͖ planes parallel the GaAs ͕110͖ planes. Diodes prepared on ͑001͒, ͑111͒B, and ͑011͒ wafers have current-voltage barrier heights ⌽ B IV that vary from 0.74, to 0.76, to 0.83 eV ͑n = 1.01-1.11͒, respectively. These barrier heights straggle values from earlier reports for polycrystalline Bi deposited by ultrahigh vacuum techniques or electrodeposition. Barrier heights measured from high frequency, capacitance-voltage characteristics are higher than the ⌽ B IV results, 0.06-1.5 eV, as a function of the GaAs orientation, increasing in value in order of ͑011͒, ͑001͒, to ͑111͒B. This is explained by a combination of image force lowering and field emission corrections, and interface state/dipoles that are likely dependent on the GaAs orientation and on the degree of ͑0001͒ Bi alignment. These results are supported by cross-sectional transmission electron microscopy investigations indicating abrupt Bi/ GaAs interfaces without evidence of a significant interfacial oxide or reacted layer.

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Section: Resultsmentioning

confidence: 98%

“…In the case of Si contacts, there are a number of low mismatch, silicide/Si ͑111͒ interfaces. 13 The presence of the ammonia sulfate likely inhibits the oxidation of the metal ions as well as the GaAs surface. These have been experimentally 1,2 and theoretically 3 correlated with Schottky barrier heights that differ by 0.14 eV.…”

Section: Introductionmentioning

confidence: 99%

Epitaxial Bi∕GaAs diodes via electrodeposition

Bao¹,

Kavanagh²

2006

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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“…A number of approaches have been used to deposit metal islands on semiconductor substrates. Typical examples include physical evaporation against templates, , which requires expensive high vacuum evaporation systems, and electrochemical − /electroless plating, ,− which usually produces metal nanoparticles coated with organic surfactant molecules. If appropriate metal precursors and semiconductor wafers are carefully chosen, simple galvanic reactions between metal precursors and semiconductors can induce direct deposition of metal nanoparticles with clean surfaces on the semiconductor wafers. − Similar galvanic reactions between metal precursors and metal substrates have also been employed to deposit metal nanoparticles on metal surfaces − and synthesize hollow nanostructures. − We recently studied the reaction between a neutral aqueous solution of AgNO 3 and single-crystalline n-type GaAs wafers with dopant (Si) concentrations higher than 1 × 10 18 cm −3 : 12AgNO 3 + 2GaAs + 6H 2 O → 12Ag + Ga 2 O 3 + As 2 O 3 + 12HNO 3 This room temperature reaction generates high-quality Ag nanoplates on the GaAs substrates. − The morphologies of the Ag structures are significantly different from those of products (i.e., Ag particles with irregular shapes) grown with acidic solutions of metal precursors .…”

Section: Introductionmentioning

confidence: 99%

“…4 A number of approaches have been used to deposit metal islands on semiconductor substrates. Typical examples include physical evaporation against templates, 4,14 which requires expensive high vacuum evaporation systems, and electrochemical [21][22][23][24] /electroless plating, 2,[25][26][27] which usually produces metal nanoparticles coated with organic surfactant molecules. If appropriate metal precursors and semiconductor wafers are carefully chosen, simple galvanic reactions between metal precursors and semiconductors can induce direct deposition of metal nanoparticles with clean surfaces on the semiconductor wafers.…”

Section: Introductionmentioning

confidence: 99%

Formation of Oxides and Their Role in the Growth of Ag Nanoplates on GaAs Substrates

2008

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Simple galvanic reactions between highly doped n-type GaAs wafers and a pure aqueous solution of AgNO 3 at room temperature provide an easy and efficient protocol to directly deposit uniform Ag nanoplates with tunable dimensions on the GaAs substrates. The anisotropic growth of the Ag nanoplates in the absence of surfactant molecules might be partially ascribed to the codeposition of oxides of gallium and arsenic, which are revealed by extensive data from electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy, during the growth of the Ag nanoplates. The electron microscopic characterization shows that each Ag nanoplate has a "necked" geometry, that is, it pins on the GaAs lattices through only a tiny neck (with sizes of <10 nm). In addition, the as-grown Ag nanoplates exhibit strong enhancement toward Raman scattering of materials on (or around) their surfaces.

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“…The latter is guaranteed through the use of middle and low-doped semiconducting substrates (N D < 1 ·10 ), which provides wide Bi/semiconductor Schottky barriers. Although Bi/n-GaAs diodes have already been obtained via electrodeposition (14) (15) (16), there are no quantum transport studies of Bi ultrathin films in this configuration. This lack of measurements could be related to a bad electrical isolation due to the high porosity of Bi ultra-thin films grown on n-GaAs electrodes.…”

Section: Introductionmentioning

confidence: 99%

Strategies to unblock the n-GaAs surface when electrodepositing Bi from acidic solutions

Prados

Ranchal

Pérez

2015

Electrochimica Acta

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Bismuth ultra-thin films grown on n-GaAs electrodes via electrodeposition are porous due to a blockade of the electrode surface caused by adsorbed hydrogen when using acidic electrolytes. In this study, we discuss the existence of two sources of hydrogen adsorption and we propose different routes to unblock the n-GaAs surface in order to improve Bi films compactness. Firstly, we demonstrate that increasing the electrolyte temperature provides compact yet polycrystalline Bi films. Cyclic voltammetry scans indicate that this low crystal quality might be a result of the incorporation of Bi hydroxides within the Bi film as a result of the temperature increase. Secondly, we have illuminated the semiconductor surface to take advantage of photogenerated holes. These photocarriers oxidize the adsorbed hydrogen unblocking the surface, but also create pits at the substrate surface that degrade the Bi/GaAs interface and prevent an epitaxial growth. Finally, we show that performing a cyclic voltammetry scan before electrodeposition enables the growth of compact Bi ultra-thin films of high crystallinity on semiconductor substrates with a doping level low enough to perform transport measurements.

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Epitaxial Bi∕GaAs(111) diodes via electrodeposition

Cited by 19 publications

References 13 publications

Epitaxial Bi∕GaAs diodes via electrodeposition

Epitaxial Bi∕GaAs diodes via electrodeposition

Formation of Oxides and Their Role in the Growth of Ag Nanoplates on GaAs Substrates

Strategies to unblock the n-GaAs surface when electrodepositing Bi from acidic solutions

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