Self-Limitation of Native Oxides Explained

Bohling, Christian; Sigmund, Wolfgang M.

doi:10.1007/s12633-015-9366-8

Cited by 37 publications

(35 citation statements)

References 28 publications

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“…Since oxygen has much higher reactivity even in the molecular form, it is bonding to the surface also in Regions II and III. It is well known that whenever silicon is exposed to oxygen, a thin amorphous film of native silicon dioxide forms on the surface with a thickness of ~1 nm …”

Section: Resultssupporting

confidence: 91%

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Periodic density fluctuations in sputtered aluminum‐doped silicon oxynitride layers

Роч

Šimurka²,

Ow‐Yang

et al. 2019

Int J of Appl Glass Sci

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Magnetron sputtering is widely used for deposition of silicon oxynitride (SiOxNy) coatings on glass in large‐area applications. Since repeated deposition simulates the factory‐scale in‐line processing, amorphous aluminum‐doped SiOxNy layers with thickness of about 250 nm were deposited by reactive pulsed DC sputtering in a multi‐pass process with repeated linear movement of a glass substrate under an Al‐alloyed Si target. Using specular X‐ray reflectivity we show periodic fluctuations of the material density throughout the entire thickness of the resulting coating. The number of periods corresponds to the number of passes of the substrate through the plasma of the magnetron. Fitting results suggest a model consistent with a periodic alternation of the O/N ratio. These subtle stoichiometric fluctuations in the SiOxNy layer composition were confirmed by scanning transmission electron microscopy analysis with nanoscale resolution, and with detailed elemental maps of characteristic X‐rays of the layered cross‐section. Our study demonstrates the superior sensitivity of the relatively simple nondestructive X‐ray reflectivity method for industrial line‐process inspection compared to ellipsometry.

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Section: Resultssupporting

confidence: 91%

“…The inset shows the density profile for the model fit exposed to oxygen, a thin amorphous film of native silicon dioxide forms on the surface with a thickness of ~1 nm. 28,29 . After such potential oxidation, no further growth takes place in Region III.…”

Section: Resultsmentioning

confidence: 99%

Periodic density fluctuations in sputtered aluminum‐doped silicon oxynitride layers

Роч

Šimurka²,

Ow‐Yang

et al. 2019

Int J of Appl Glass Sci

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Section: Experiments and Resultsmentioning

confidence: 99%

“…In the transfer of the sample to the chamber, some native oxide will form. It has been well documented that the native oxide formed on silicon is limited to a few nanometers; [44] experiments have shown freshly etched silicon to have a growth of oxide 1 nm thick after a few hours and remaining at that thickness after 24 h exposure to air at 24 C. [45] We measured the dark count rate K detected by the SE detector by blanking the beam and looking for events. In several experiments with a total integration time of 0.1 s, the number of dark count event detections was %1, i.e., K % 10 À5 counts per μs.…”

Section: Experiments and Resultsmentioning

confidence: 99%

Single Ion Implantation of Bismuth

Cassidy

Blenkinsopp

Brown

et al. 2020

Physica Status Solidi (a)

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Herein, the results from a focused ion beam instrument, designed to implant single ions with a view to the fabrication of qubits for quantum technologies, are presented. The difficulty of single ion implantation is accurately counting the ion impacts. This is achieved here through the detection of secondary electrons generated upon each ion impact. The implantation of single bismuth ions with different charge states into Si, Ge, Cu, and Au substrates is reported, and the counting detection efficiency for single ion implants and the factors that affect such detection efficiencies are determined. It is found that for 50 keV implants of Bi++ ions into silicon an 89% detection efficiency can be achieved, which is the first quantitative detection efficiency measurement for single ion implants into silicon without implanting through a thick SiO2 film. This level of counting accuracy provides implantation of single impurity ions with a success rate significantly exceeding that achievable by random (Poissonian) implantation.

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“…The reason for the change in characteristics during long-term storage (i.e., two years) may be the influence of atmospheric oxygen on natural oxides, which are formed on the outer surfaces of nanowire sensor elements. Bohling has shown that the properties of an oxide can change dramatically upon contact with the environment [22], and the mechanism causing the difference in response from the freshly prepared chip with that from the chip stored for two years could be explained in the following way. On the surface of a freshly prepared chip, the molecules of covalently immobilized oDNA probes can have an arcuate shape (reaching to the surface of the chip), as the negatively charged bases are attracted to the positively charged nanowire surface, whose positive net charge is caused by application of positive voltage to the gate.…”

Section: Discussionmentioning

confidence: 99%

Detection of Marker miRNAs, Associated with Prostate Cancer, in Plasma Using SOI-NW Biosensor in Direct and Inversion Modes

Ivanov

Pleshakova

Malsagova

et al. 2019

Sensors

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Information about the characteristics of measuring chips according to their storage conditions is of great importance for clinical diagnosis. In our present work, we have studied the capability of chips to detect nanowire biosensors when they are either freshly prepared or have been stored for either one or two years in a clean room. Potential to detect DNA oligonucleotides (oDNAs)—synthetic analogues of microRNAs (miRNAs) 198 and 429 that are associated with the development of prostate cancer (PCa)—in buffer solution was demonstrated using a nanowire biosensor based on silicon-on-insulator structures (SOI-NW biosensor). To provide biospecific detection, nanowire surfaces were sensitized with oligonucleotide probes (oDNA probes) complimentary to the known sequences of miRNA 183 and 484. In this study it is demonstrated that freshly prepared SOI-NW biosensor chips with n-type conductance and immobilized oDNA probes exhibit responses to the addition of complimentary oDNAs in buffer, leading to decreases in chips’ conductance at a concentration of 3.3 × 10−16 M. The influence of storage time on the characteristics of SOI-NW biosensor chips is also studied herein. It is shown that a two-year storage of the chips leads to significant changes in their characteristics, resulting in “inverse” sensitivity toward negatively charged oDNA probes (i.e., through an increase in chips’ conductance). It is concluded that the surface layer makes the main contribution to conductance of the biosensor chip. Our results indicate that the detection of target nucleic acid molecules can be carried out with high sensitivity using sensor chips after long-term storage, but that changes in their surface properties, which lead to inversed detection signals, must be taken into account. Examples of the applications of such chips for the detection of cancer-associated microRNAs in plasma samples of patients with diagnosed prostate cancer are given. The results obtained herein are useful for the development of highly sensitive nanowire-based diagnostic systems for the revelation of (prostate) cancer-associated microRNAs in human plasma.

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Self-Limitation of Native Oxides Explained

Cited by 37 publications

References 28 publications

Periodic density fluctuations in sputtered aluminum‐doped silicon oxynitride layers

Periodic density fluctuations in sputtered aluminum‐doped silicon oxynitride layers

Single Ion Implantation of Bismuth

Detection of Marker miRNAs, Associated with Prostate Cancer, in Plasma Using SOI-NW Biosensor in Direct and Inversion Modes

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