Imec

Imec Vzw

Katholieke Universiteit Leuven

Katholieke Universiteit Leuven, Ku Leuven R&d

Katholieke Universitiet

Katholieke Universiteit Leuven, K.u. Leuven Research & Development

Steven Brems

Paul Mertens

Cedric Huyghebaert

Stefan De Gendt

Thomas Nuytten

Ken Verguts

Elisabeth Camerotto

Marc Hauptmann

Alessandra Leonhardt

Cesar Javier Lockhart De La Rosa

A spot on a layer of a 2D semiconductor material deposited on a substrate is irradiated so as to generate excitons, so that photons are emitted from the layer. The photoluminescence spectrum is recorded for different values of the charge carrier concentration in the layer. The modulation of the charge carrier concentration may be realized by modulating the output power of the light source used to irradiate the sample. The relation is recorded between the ratio of the photoluminescence intensity of a first peak in the spectrum related to radiative recombination from indirect bandgaps to the intensity of a second peak in the spectrum related to radiative recombination from direct bandgaps, and the carrier concentration. This relation is fitted to a model of the ratio that takes into account multiple recombination mechanisms, radiative and non-radiative. From this process, the trap density within the bandgap is derived.

Method for measuring the trap density in a 2-dimensional semiconductor material

The disclosed technology generally relates to preparing two-dimensional material layers, and more particularly to releasing a graphene layer from a template substrate. According to an aspect, a method of releasing a graphene layer includes providing a template substrate on which the graphene layer is provided, the method comprising: subjecting the graphene layer and the template substrate to a water treatment by soaking the graphene layer and the template substrate in water such that water is intercalated between the template substrate and the graphene layer; and subjecting the graphene layer and the template substrate to a delamination process, thereby releasing the graphene layer from the template substrate.

Method of releasing graphene from substrate

This present application relates to a system for delivering megasonic energy to a liquid, involving one or more megasonic transducers, each transducer having a single operating frequency within an ultrasound bandwidth and comprising two or more groups of piezoelectric elements arranged in one or more rows, and a megasonic generator means for driving the one or more transducers at frequencies within the bandwidth, the generator means being adapted for changing the voltage applied to each group of piezoelectric elements so as to achieve substantially the same maximum acoustic pressure for each group of piezoelectric elements. The generator means and transducers being constructed and arranged so as to produce ultrasound within the liquid. Such a system may be part of an apparatus for cleaning a surface of an article such as a semiconductor wafer or a medical implant.

System for delivering ultrasonic energy to a liquid and use for cleaning of solid parts

The present invention is related to a method and apparatus for cleaning a substrate, in particular a semiconductor substrate such as a silicon wafer. The substrate is placed in a tank containing a cleaning liquid, at an angle with respect to acoustic waves produced in said liquid. The angle corresponds to the angle of transmission, i.e. the angle at which waves are not reflected off the substrate surface. A damping material is provided in the tank, arranged to absorb substantially all waves thus transmitted through the substrate. A significant improvement in terms of cleaning efficiency is obtained by the method of the invention.

Method and apparatus for cleaning semiconductor substrates

Methods and apparatuses for cleaning a surface of a substrate are presented. The method comprises positioning a substrate at a controllable distance from a piezoelectric transducer, supplying a cleaning liquid between the substrate and the transducer, applying an oscillating acoustic force to the cleaning liquid by actuating the transducer, and moving the transducer relative to the substrate. The method further comprises, while moving the transducer relative to the substrate, measuring a value that indicates a distance between a surface of the substrate and the transducer, comparing the measured value to a desired value, and adjusting the distance between the surface and the transducer so that the measured value is maintained substantially equal to the desired value. The measured value may be the distance between the surface of the substrate and the transducer or a phase shift between an alternating current and voltage applied to the transducer.

Method and apparatus for controlling optimal operation of acoustic cleaning

Growing community of inventors

Kessel-lo, Belgium

Steven Brems