Si(100) Etching in Aqueous Fluoride Solutions: Parallel Etching Reactions Lead to pH-Dependent Nanohillock Formation or Atomically Flat Surfaces

Aldinger, Brandon S.; Hines, Melissa A.

doi:10.1021/jp308064s

Cited by 13 publications

(9 citation statements)

References 42 publications

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“…44 Chemical means have also been attempted by etching in aqueous NH 4 F (40 %), although atomics steps were not observed. 74 2. The SiO 2 /Al 2 O 3 interface -fixed charge in Al 2 O 3…”

Section: The Si/sio 2 Interfacementioning

confidence: 99%

A fabrication guide for planar silicon quantum dot heterostructures

Spruijtenburg¹,

Amitonov²,

Wiel³

et al. 2018

Nanotechnology

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We describe important considerations to create top-down fabricated planar quantum dots in silicon, often not discussed in detail in literature. The subtle interplay between intrinsic material properties, interfaces and fabrication processes plays a crucial role in the formation of electrostatically defined quantum dots. Processes such as oxidation, physical vapor deposition and atomic-layer deposition must be tailored in order to prevent unwanted side effects such as defects, disorder and dewetting. In two directly related manuscripts written in parallel we use techniques described in this work to create depletion-mode quantum dots in intrinsic silicon, and low-disorder silicon quantum dots defined with palladium gates. While we discuss three different planar gate structures, the general principles also apply to 0D and 1D systems, such as self-assembled islands and nanowires. 1 arXiv:1709.08866v3 [cond-mat.mes-hall] Feb 2018Dealing with the fragility of the quantum coherent state is one of the key issues on the road to meet the limits posited by quantum computation schemes 1 . It is the coupling of quantum states to states in an unknown environment which is the driver for decoherence. The properties of the environment therefore dictate the performance of a quantum bit (qubit).Creating qubits in the solid state means that the environment consists of many different materials and structures used in device construction. give rise to interactions detrimental to qubit creation and readout.The hyperfine interaction of nuclear spins in the host material and the qubit is one such effect. The non-zero-spin isotopes in a material create a nuclear-spin-bath and cause decoherence of the quantum state. This is the motivation for the use of isotopically purified silicon as a host material for spin qubits 9,10 . The purified silicon, now containing predomi-Si, results in a zero-nuclear-spin isotope system, and eliminates the fluctuations in the spin bath, which are detrimental.Field noise, such as charge-and spin-noise 11 can also influence the lifetime of the quantum state. One strategy to deal with these fluctuations is to tune the quantum dots to certain regimes in phase space where the energy levels of interest are insensitive to these fields. This can happen in the clock transition of Bi dopants in Si 12 , by dressing qubits and tuning them appropriately 13 , or for hybrid quantum dots. 14 Another effect that can influence quantum states are fluctuations in the electrochemical potential at longer timescales. These have been shown to occur due to charge offsets fluctuating over time in glassy media and their intrinsic two-level systems (TLS). 15,16Finally, unintentional quantum dots, charge traps, or charge defects can influence a de- This article has the intention to provide a foothold for entrants in the field (e.g. starting graduate students) and elucidate mechanisms that need to be taken into account when designing and fabricating these devices in the solid state. It can be read back to front, and may also serve well ...

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“…44 Chemical means have also been attempted by etching in aqueous NH 4 F (40 %), although atomics steps were not observed. 74 2. The SiO 2 /Al 2 O 3 interface -fixed charge in Al 2 O 3…”

Section: The Si/sio 2 Interfacementioning

confidence: 99%

A fabrication guide for planar silicon quantum dot heterostructures

Spruijtenburg¹,

Amitonov²,

Wiel³

et al. 2018

Nanotechnology

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“…As an example, Cartesian decomposition of the Si–H vibrational spectrum on etched Si(100) wafers disproved a long-standing and much-cited spectral assignment that postulated the production of a rough, disordered surface, revealing instead the production of a near-atomically flat surface. Similarly, the technique was used to uncover the mechanism of pH-induced surface roughening during Si(100) etching, revealing the production of faceted nanohillocks at low pH …”

Section: Introductionmentioning

confidence: 99%

Cartesian Decomposition of Infrared Spectra Reveals the Structure of Solution-Deposited, Self-Assembled Benzoate and Alkanoate Monolayers on Rutile (110)

et al. 2016

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Cartesian polarization analysis transforms a set of surface infrared spectra obtained in different geometries into their Cartesian components using a mathematical transform, providing direct insight into the bonding geometry of adsorbed molecules. This technique was extended to uniaxial substrates and used to analyze solution-deposited, self-assembled benzoate and alkanoate monolayers on rutile (110). This analysis resolved a long-standing controversy regarding the existence of paired molecules in benzoate monolayers, showing that two distinct isomers exist within the monolayer: a tilted tetramer, which is paired, and a twisted monomer, which is not. The two isomers are nearly isoenergetic, as shown by analysis of STM images and complementary DFT simulations. Infrared and XPS spectra as well as STM images of heptanoate and octanoate monolayers showed the formation of complete monolayers (as opposed to sparse layers or multilayers); however, the alkyl chains in the monolayer are disordered and loosely packed with a significant density of conformational defectsa stark contrast to the near-crystalline, all-trans alkyl monolayers typically formed on Au and Si surfaces. The high disorder in the alkanoate monolayers was attributed to geometry, as the density of alkanoate binding sites on rutile (110) is 30% less than the density of alkyl monolayers on Si. The high density of gauche defects in alkanoate monolayers was attributed to the small energy difference between the all-trans and single-gauche-defect conformers in isolated alkyl chains. In contrast, strong intermolecular interactions in tight-packed alkyl monolayers on Au and Si surfaces suppress gauche defect formation.

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“…In order to produce the desired stable interfaces, silicon surfaces terminated with hydrogen or halogen are commonly used as starting points. Recent work on preparation and characterization of H-terminated − and Cl-terminated − Si(100) and Si(111) single crystalline surfaces allows for a detailed understanding of the chemical processes with a truly molecular level precision. The functionalization step commonly includes the reactions of these modified silicon surfaces with appropriate organic reagents to produce stable organic monolayers that can, in turn, be further modified to yield nearly any chemical or biological functionality needed. ,− …”

Section: Introductionmentioning

confidence: 99%

Dehydrohalogenation Condensation Reaction of Phenylhydrazine with Cl-Terminated Si(111) Surfaces

Gao

Teplyakov

2016

J. Phys. Chem. C

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Formation of stable organic–inorganic contacts with silicon often requires oxygen- and carbon-free interfaces. Some of the general approaches to create such interfaces rely on the formation of a Si–N bond. A reaction of dehydrohalogenation condensation of Cl-terminated Si(111) surface with phenylhydrazine is investigated as a means to introduce a simple function to the surface using a –NH-NH2 moiety as opposed to previously investigated approaches. The use of substituted hydrazine allows for the formation of a stable structure that is less strained compared to the previously investigated primary amines and leads to minimal surface oxidation. The process is confirmed by a combination of infrared studies, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry investigations. Density functional theory is utilized to yield a plausible surface reaction mechanism and provide a set of experimental observables to compare with these data.

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Si(100) Etching in Aqueous Fluoride Solutions: Parallel Etching Reactions Lead to pH-Dependent Nanohillock Formation or Atomically Flat Surfaces

Cited by 13 publications

References 42 publications

A fabrication guide for planar silicon quantum dot heterostructures

A fabrication guide for planar silicon quantum dot heterostructures

Cartesian Decomposition of Infrared Spectra Reveals the Structure of Solution-Deposited, Self-Assembled Benzoate and Alkanoate Monolayers on Rutile (110)

Dehydrohalogenation Condensation Reaction of Phenylhydrazine with Cl-Terminated Si(111) Surfaces

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