Patrik Willi Hoffmann

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In atomic layer deposition processes (ALD), surface reactions of adsorbed precursor species lead to the formation of thin films. In order to achieve a well-controlled, self-limiting process, the substrate is sequentially exposed to different precursor mole ...

We report, to our knowledge, the first active channel waveguide in Ti:sapphire. We have created [similar to] 1.4-μm high ribs in a [similar to] 10-μm thick Ti:sapphire planar waveguide by reactive ion etching. Following excitation by an Ar-ion laser, the rib structure showed channel-waveguide fluorescence emission. The mode profiles and the beam-parameter values (M2) were measured. The coupling efficiency of fluorescence emission into a single-mode fiber was an order of magnitude higher than for fluorescenc

Selective dissolution of titanium through a laser patterned oxide film has been achieved in a 3M sulfuric acid-methanol electrolyte. The 250 nm thick oxide film was formed anodically on a flat titanium surface in 0.5 M sulfuric acid. The patterning of the film was obtained by local irradiation using a long pulse XeCl eximer laser. Electrochemical dissolution at irradiated lines on the oxide film yielded well-defined grooves comparable to those resulting from electrochemical micromachining through a photores

Combinatorial high-vacuum chemical vapor deposition (HV-CVD) was used to identify the conditions required to obtain hafnium-doped lithium niobate thin films on sapphire {001} substrates. Niobium tetraethoxydimethylaminoethoxide (Nb(OEt)(4)(dmae)), lithium tert-butoxide (Li(OBut)), and hafnium tert-butoxide (Hf(OBut)(4)) were used as precursors. X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicated that a single phase of textured {001} Hf-doped lithium niobate film was obtained under c

A method and apparatus for local beam processing using a beam activated gas to etch material are described. Compounds are disclosed that are suitable for beam-induced etching. The invention is particularly suitable for electron beam induced etching of chro ...

Synthesizing high-quality epitaxial BaTiO3 (BTO) by means of high-vacuum chemical vapor deposition (HV-CVD) requires a precise control over precursor fluxes impinging onto the heated substrate surface so that the incorporation rates of all elements corresp ...

The invention relates to a device for producing a gas mixture consisting of HMDSO and oxygen, whereby process gas is produced. In order to be able to continuously produce a large volume of process gas using such a device and to be able to withdraw the same at practical processable temperatures, the invention provides that a number of filling packages (2) are stacked in an elongated essentially vertical column (1) that can be cooled. In addition, an inlet tube (3), which is inserted into the column (1) from

Codeposition of hydrocarbons is a severe problem during focused electron beam writing of pure metal nanostructures. When using organometallic precursors, a low metal content carbonaceous matrix embedding and separating numerous nanosized metal clusters is formed. In this work, we present a new and easy approach to obtain high purity gold lines: the use of inorganic PF3AuCl as a precursor. Electrical resistivities as low as 22 µOhms cm at 295 K (ten times the bulk Au value) were obtained. This is to our know

A method for the gas phase deposition of partially fluorinated or perfluorinated alkyl silanes onto a substrate in a reaction chamber includes cleaning the substrate, hydrating the substrate with steam, drying the substrate and silanization of the substrate by deposition of the alkyl silane from the gas phase. The cleaning of the substrate is a plasma etching process and the hydration occurs directly after the plasma etching.

The spatial evolution of compositions and sub-structures inside focused-electron-beam-deposited tips from dicobalt-octacarbonyl Co2(CO)8 precursor at 25 keV and varying beam current (20 pA - 3 A) is extensively studied for the first time by means of energy ...

The deposition of amorphous alumina (Al2O3) films on four inch wafers with high deposition rate (up to 50 nm/min) by an advanced HV-CVD technique is discussed. Amorphous nature of the films is confirmed by X-ray diffraction. Refractive index of the deposited alumina can be adjusted in the large range (1.3-1.62@633 nm) by varying the substrate temperate during the deposition. The films are highly transparent. The density and stoichiometry of the deposits are also influenced by deposition conditions. Presence

Spin-coated solid films of the gold-cluster compd. dodeca-(triphenylphosphine), hexa(chloro)pentapentacontagold Au55(PPh3)12Cl6 are irradiated with a focused 20-keV Ga+ focused-ion beam. Writing speeds on the substrate ranged from 50 up to 2000 mm/s. This treatment locally decreases the soly. of the metalorg. precursor layer in CH2Cl2. Removal of the nonirradiated part of the surface layer with this solvent, followed by thermal decompn. of the remaining metalorg. nanostructures, leads to conducting gold lin

Combinatorial lithium niobate deposition on 150 mm naturally oxidized silicon (100) wafers in a high-vacuum chemical vapor deposition reactor using Li(OBut) and Nb(OEt)4(dmae) is presented. The novel precursor supply system allows individual spatial control of precursors impinging rates on the substrate. This results in variations of the film properties in a single experiment at a certain substrate temperature due to the influence of different precursors flow rates and ratios. It efficiently leads to deposi

Diamond growth on a (100) oriented Si substrate by a laser-induced chem. transport reaction (LICTR) method is described. SEM indicated that the LICTR-deposited diamonds had a cubic structure. Their Raman spectrum obsd. at Stokes shifts between 1300 and 1370 cm-1 showed a single sharp line with the position and full width at half-max. very close to those of natural diamond. These results contrast with those obtained for diamond produced by hot-filament CVD.

A systematic study of niobium oxide deposition using niobium tetraethoxy-dimethyl-amino-ethoxide (Nb(OEt)(4)(dmae)) precursor is presented. The deposition process was conducted in a high-vacuum chemical vapor deposition machine with precursor flux gradient capability. An efficient optimization of the deposition process was achieved and both mass-transport- and chemical-reaction-limited regimes were identified.

We report on the fabrication of Ti:sapphire channel waveguides. Such channel waveguides are of interest, e.g., as low-threshold tunable lasers. We investigated several structuring methods including ion beam implantation followed by wet chemical etching strip loading by polyimide spin coating and subsequent laser micro-machining, direct laser ablation or reactive ion etching through laser-structured polyimide contact masks. The later two methods result in ribs having different widths and heights up to simila

Combinatorial high vacuum chemical vapor deposition (HV-CVD) of mixed HfO2-Nb2O5 thin films has been demonstrated to yield amorphous layers at substrate temperatures where individually deposited pure HfO2 and Nb2O5 films are polycrystalline. Spectroscopic ...

Patrik Willi Hoffmann

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Surface Reaction Kinetics of Titanium Isopropoxide and Water in Atomic Layer Deposition

Ti:sapphire rib channel waveguide fabricated by reactive ion etching of a planar waveguide

Electrochemical Micromachining of Titanium through a Laser Patterned Oxide Film

Combinatorial High-Vacuum Chemical Vapor Deposition of Textured Hafnium-Doped Lithium Niobate Thin Films on Sapphire

Beam-induced etching of material on substrate involves directing gaseous compound which reacts in the presence of beam to etch the excess material which not etching the substrate

High-quality epitaxial BaTiO3 films grown by high-vacuum chemical vapor deposition for integrated electro-optical devices

Apparatus for producing gas mixture from hexamethyldisiloxane and carrier gas, e.g. oxygen, as process gas comprises filling packing arranged in a vertical column which can be cooled

Focused electron beam induced deposition of gold

Coated, light-transmitting or reflecting substrate, used as optical component or window, e.g. lens, mirror or windscreen, has (per)fluoroalkylsilane coating produced by plasma etching, hydration, drying and gas phase deposition

Cross section investigations of compositions and sub-structures of tips obtained by focused electron beam induced deposition

Tailoring of Optical Properties of Alumina films deposited by High Vacuum CVD (HV-CVD)

Vorrichtung zum Herstellen eines Gasgemisches

Vorrichtung zum Herstellen eines Gasgemisches

Device for producing a gas mixture

Direct writing of gold nanostructures using a gold-cluster compound and a focused ion beam

Combinatorial Chemical Vapor Deposition of Lithium Niobate Thin Films

A laser-induced chemical transport reaction method for diamond deposition

Efficient optimization of high vacuum chemical vapor deposition of niobium oxide on full wafer scale

Laser-assisted microstructuring for Ti : sapphire channel-waveguide fabrication

Combinatorial Discovery and Optimization of Amorphous HfO2-Nb2O5 Mixture with Improved Transparency