Evidence for liquid indium nanoparticles on Ge(001) at room temperature

Bottomley, D. J.; Iwami, M; Uehara, Y.; Ushioda, S.

doi:10.1116/1.590511

Cited by 9 publications

(11 citation statements)

References 27 publications

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“…1,2 A recent study of P doped Ge͑100͒ suggested an alternative explanation; that P segregates to the surface during annealing and forms GeP 3 which then appears as nanoscale white dots on the surface. 4 Their STM images were similar to ours with many white protrusions and holes suggesting a similar origin, even though there was no evidence of the presence of P, or any other impurity, in our AES data and our wafer was undoped. Thus, it is unclear if the white dots observed in the recent study were indeed GeP 3 or trace contaminants or defects commonly observed on Ge͑100͒ surfaces.…”

Section: A Ion Bombardment and Annealingsupporting

confidence: 75%

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Development of procedures for obtaining clean, low-defect-density Ge(100) surfaces

Chan¹,

Altman²,

Liang³

2001

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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A repeatable, in situ process was developed for preparing clean, low-defect-density Ge(100) surfaces based on scanning tunneling microscopy (STM), Auger electron spectroscopy (AES), and x-ray photoelectron spectroscopy (XPS) measurements. Surfaces prepared by ion sputtering followed by annealing, wet chemical etching followed by oxidation and thermal desorption of the oxide layer, growth of a Ge buffer layer, and in situ plasma cleaning were compared. The first two methods produced surfaces with no impurities detectable by AES, however, STM images of the surfaces revealed numerous protrusions, vacancies, and other defects. Auger electron spectra and STM images recorded before and after annealing C contaminated surfaces suggested that the protrusions were three-dimensional C clusters formed at elevated temperatures. The low surface to volume ratio of the clusters makes them difficult to detect by either XPS or AES. Although XPS indicated that oxygen plasma treatment effectively removes C from Ge surfaces, images of the plasma treated surfaces still showed the protrusions attributed to C. In contrast, surfaces prepared by Ge buffer layer growth followed by annealing exhibited no protrusions, low-defect densities on the terraces (less than 2% of a monolayer), and evenly spaced terraces that reflect the misorientation of the crystal. Thus, the surfaces prepared by Ge buffer layer growth were determined to be the most suitable for atomic level nucleation and growth studies.

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Section: A Ion Bombardment and Annealingsupporting

confidence: 75%

“…In other work, surface protrusions were attributed to surface segregation of dopants. 4 The protrusions, however, appeared very similar to those observed on undoped samples, thus raising questions about the assignment of the features to dopant segregation. The step pinning by the protrusions can also lead to problems.…”

Section: Introductionmentioning

confidence: 69%

Development of procedures for obtaining clean, low-defect-density Ge(100) surfaces

Chan¹,

Altman²,

Liang³

2001

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…XXXX, XXX, XXX−XXX at room temperature. 50 For this reason, we evaluated their capacity to facilitate ec-LLS crystal growth. We first prepared In nanoparticles on degenerately doped n-type Si(100) (n + -Si(100)) wafers via pulse electroplating.…”

Section: Accounts Of Chemical Researchmentioning

confidence: 99%

Electrochemical Liquid–Liquid–Solid (ec-LLS) Crystal Growth: A Low-Temperature Strategy for Covalent Semiconductor Crystal Growth

Fahrenkrug

Maldonado

2015

Acc. Chem. Res.

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This Account describes a new electrochemical synthetic strategy for direct growth of crystalline covalent group IV and III-V semiconductor materials at or near ambient temperature conditions. This strategy, which we call "electrochemical liquid-liquid-solid" (ec-LLS) crystal growth, marries the semiconductor solvation properties of liquid metal melts with the utility and simplicity of conventional electrodeposition. A low-temperature liquid metal (i.e., Hg, Ga, or alloy thereof) acts simultaneously as the source of electrons for the heterogeneous reduction of oxidized semiconductor precursors dissolved in an electrolyte as well as the solvent for dissolution of the zero-valent semiconductor. Supersaturation of the semiconductor in the liquid metal triggers eventual crystal nucleation and growth. In this way, the liquid electrolyte-liquid metal-solid crystal phase boundary strongly influences crystal growth. As a synthetic strategy, ec-LLS has several intrinsic features that are attractive for preparing covalent semiconductor crystals. First, ec-LLS does not require high temperatures, toxic precursors, or high-energy-density semiconductor reagents. This largely simplifies equipment complexity and expense. In practice, ec-LLS can be performed with only a beaker filled with electrolyte and an electrical circuit capable of supplying a defined current (e.g., a battery in series with a resistor). By this same token, ec-LLS is compatible with thermally and chemically sensitive substrates (e.g., plastics) that cannot be used as deposition substrates in conventional syntheses of covalent semiconductors. Second, ec-LLS affords control over a host of crystal shapes and sizes through simple changes in common experimental parameters. As described in detail herein, large and small semiconductor crystals can be grown both homogeneously within a liquid metal electrode and heterogeneously at the interface of a liquid metal electrode and a seed substrate, depending on the particular details chosen for ec-LLS. Third, the rate of introduction of zero-valent materials into the liquid metal is precisely gated with a high degree of resolution by the applied potential/current. The intent of this Account is to summarize the key elements of ec-LLS identified to date, first contextualizing this method with respect to other semiconductor crystal growth methods and then highlighting some unique capabilities of ec-LLS. Specifically, we detail ec-LLS as a platform to prepare Ge and Si crystals from bulk- (∼1 cm(3)), micro- (∼10(-10) cm(3)), and nano-sized (∼10(-16) cm(3)) liquid metal electrodes in common solvents at low temperature. In addition, we describe our successes in the preparation of more compositionally complex binary covalent III-V semiconductors.

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“…The thermodynamically stable shape of the islands is determined by the energies of the surface facets, facet edges, and interfaces [1][2]. To control the size and shape of the island, these energies can be modified, possibly by introducing additional species onto the growing surface [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Effect Of Phosphorus On Ge/Si(001) Island Formation

et al. 2002

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When Ge is deposited epitaxially on Si, the strain energy from the lattice mismatch causes the Ge in layers thicker than about four monolayers to form distinctive, three-dimensional islands. The shape of the islands is determined by the energies of the surface facets, facet edges, and interfaces. When phosphorus is added during the deposition, the surface energies change, modifying the island shapes and sizes, as well as the deposition process. When phosphine is introduced to the germane/hydrogen ambient during Ge deposition, the deposition rate decreases because of competitive adsorption. The steady-state deposition rate is not reached for thin layers. The deposited, doped layers contain three different island shapes, as do undoped layers; however, the island size for each shape is smaller for the doped layers than for the corresponding undoped layers. The intermediate-size islands are the most significant; the intermediate-size doped islands are of the same family as the undoped, multifaceted “dome” structures, but are considerably smaller. The largest doped islands appear to be related to the defective “superdomes” discussed for undoped islands. The distribution between the different island shapes depends on the phosphine partial pressure. At higher partial pressures, the smaller structures are absent. Phosphorus appears to act as a mild surfactant, suppressing small islands.

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Evidence for liquid indium nanoparticles on Ge(001) at room temperature

Cited by 9 publications

References 27 publications

Development of procedures for obtaining clean, low-defect-density Ge(100) surfaces

Development of procedures for obtaining clean, low-defect-density Ge(100) surfaces

Electrochemical Liquid–Liquid–Solid (ec-LLS) Crystal Growth: A Low-Temperature Strategy for Covalent Semiconductor Crystal Growth

Effect Of Phosphorus On Ge/Si(001) Island Formation

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