DFG Terahertz Core Facility

DFG-Terahertz Core Facility

Welcome to the DFG Core Facility for 6G and THz Research (6Gcore) at the University of Wuppertal, a pioneering institution promoting scientific research and interdisciplinary collaboration in the region. Our goal is to push the frontiers of knowledge by providing state-of-the-art facilities and resources to support groundbreaking research in a variety of disciplines. As a centre for innovation, the DFG Core Centre brings together leading experts from different disciplines and fosters a vibrant community of scientists working together to address the most pressing challenges of our time.
The Core Centre is a new platform and offers internal and external users a wide range of specialised systems to optimally support users in their research projects in a cost-effective manner. Companies and scientific institutions are served from a single source here at the centre.
For the booking of laboratories and equipment, you will find information below about the technical equipment and the competences of the Core Centre.

To get a quick overview, you can use the following navigation:

Equipment
Measurement methods

Equipment

ISO Class 5 soft cleanrooms

Cleanrooms are divided into special cleanroom classes (cleanliness classes) depending on the particle density. They are subject to strict, standardised requirements for the maximum permissible particle concentration (particles per m³ of air) and particle size and are classified according to the degree of air purity. ISO class 5 means max. 100,000 particles ≥ 0.1 µm, 23,700 particles ≥ 0.2 µm, 1,020 particles ≥ 0.3 µm, 352 particles ≥ 0.5 µm, 83 particles ≥ 1.0 µm, no particles ≥ 5.0 µm.

Drying oven with vacuum and inert gas connection

The samples can be heated up to 200°C. At the same time, it is possible to generate an oil-free vacuum up to approx. 50mbar absolute pressure in the 23l furnace chamber. The chamber can be divided into several areas by adjustable shelves. The spatial temperature deviation is less than 3K, whereas the temporal temperature drift is less than 1K. Ventilation is done with high purity inert gas.

Low-temperature freezer

For long-term storage of adhesives and biological samples we have a large freezer with a storage temperature of -40°C.

Various microscopes with attached camera

The surface inspection by means of a camera also enables the necessary documentation of the process steps. The systems also have the option of composing image sections vertically and horizontally if the objects are larger than the image area in the selected resolution or have larger height differences which are outside the depth of field.

Black body emitter

In addition to generating IR radiation in the range 50-1,000°C, special terahertz filters (0-1THz, 0-2THz and 0-3THz) can also be used to generate and examine chopped radiation. This is of great interest e.g. for passive imaging in this frequency range.

Wafer saw

The in-house wafer saw enables the separation of individual layouts from prototype wafers. Primarily silicon samples are processed, but by using suitable saw blades, cuts in ceramics with a precision <10µm are also possible.

Various bonding technologies

In addition to the thermo-compression wire bonder for contacting the chips to the housing or board, the flip-chip technology is also used.

3D measuring technology

Two six-axis robots support the spatial acquisition of signals at almost any distance on optical tables on a laboratory scale.

Absolute power meters for high-frequency signals

The free-space absolute measuring device is suitable for the frequency range 30-30,000 GHz. Here, chopped measurements up to 100mW can be made. The system adapted to a waveguide measures calorimetrically in the frequency range 75-3,000GHz at up to 200mW radiated power.

Signal generators

Programmable digital waveform generators can produce one-time and/or continuously recurring arbitrarily shaped signals up to 20GHz. The signal can be vertically resolved with 10bit. The readout speed is max. 50GS/s, whereby the signal can consist of up to 2^35 single values (32GS).

High-performance digital oscilloscopes

Several systems with a single channel resolution of 200GS/s up to 70GHz are available. In addition, other oscilloscopes of lower bandwidth and resolution are available.

Semiconductor storage cabinets

For long-term storage of samples we have two dry storage cabinets with active reduction of humidity to < 1% relative humidity.

Measurement Methods

On chip measurements

With the help of various measuring tips, high-frequency semiconductor structures can be directly contacted and examined before they are inserted into an enclosure. Signal evaluation is carried out using various network or spectrum analysers in the 10MHz - 67GHz range. By means of additional extender also in the D- and J-band and beyond up to 1,100GHz (limited by the available measuring peaks).

Investigation of different modulation and transmission modes for communication technology

The good infrastructure allows the detailed investigation of complex modulation methods, even at high carrier frequencies. Here are some common measurement techniques used to characterise modulation techniques:

Spectral analysis: Spectral analysis is used to study the frequency spectrum of a modulated signal. Here, the signal is broken down into its various frequency components. Spectrum analysers can be used to analyse the distribution of signal energy across different frequency ranges. This allows the identification of carrier frequency, sidebands, bandwidth and other spectral characteristics of the modulation.

Eye diagram: The eye diagram is a graphical tool for assessing signal quality in digital modulation systems. It represents the superposition of several signal bits in the time domain. The eye diagram enables the analysis of transmission problems such as noise, jitter and distortion. The eye diagram can be used to evaluate parameters such as rise and fall times, eye-opening width and inter-symbol interference.

Error vector measurements: Error vector measurements are used with digital modulation techniques such as QPSK (quadrature phase shift), 16-QAM (16-fold amplitude modulation) and others. Here, the received signal is compared with an ideal reference signal and the differences between them are measured. Important parameters include the error vector magnitude (EVM) and the error vector angle (EVA), which provide information about the accuracy of the modulation.

Bit error rate (BER): The bit error rate is a commonly used metric for assessing the quality of digital modulation systems. It indicates how many erroneous bits occur in relation to the total number of bits transmitted. By measuring BER, conclusions can be drawn about the performance and susceptibility to interference of the modulation system.

Performance measurements: In modulation techniques, it is important to measure the transmission power. This includes measuring the transmitted power to ensure it meets specifications, and measuring the received power to assess signal-to-noise ratios (SNR) and other transmission losses.

Measuring range extensions

By using the additional extender, the measuring range of the analyser can be significantly extended. A distinction is made between generator and analyser systems. In addition to the established 110-170 GHz (D-band) and 220-325 GHz (J-band) systems, newer systems for the frequency range 330-500 GHz, 500-750 GHz and 1,100-1,500 GHz are also used, which can be used in the upper frequency range between -20/-10 dBm.

Use of the terahertz range for data transmission and imaging by transmitters and receivers

Terahertz imaging offers several advantages because terahertz radiation can penetrate many non-metallic materials such as plastics, paper, clothing and ceramics. At the same time, it is absorbed by many other materials such as metals, water and certain chemical compounds, which makes it possible to identify and distinguish between different substances.

Terahertz imaging uses different techniques to obtain information about the objects under investigation:

Time domain imaging: In this method, a short terahertz pulse sequence is generated and directed at the object under investigation. The reflected or transmitted terahertz pulse is detected with a detector and analysed. By detecting the time of flight of the terahertz pulse, information about the thickness, structure and reflective properties of the object can be obtained.

Frequency domain imaging: Here, a broadband terahertz signal is generated and split into different frequency components. By measuring the absorption, reflection or scattering of the terahertz radiation as a function of frequency, detailed spectral information about the object can be obtained. This enables the identification of specific chemical or material properties.

Tomography: Terahertz tomography combines different angular or positional projections to produce a three-dimensional image of the object under investigation. By combining several individual images from different angles, the internal structure of the object can be reconstructed.

We offer the use of various commercial and own terahertz systems of different power classes as single-frequency and tunable systems (-25dBm to 4dBm) and sizes (mignon cell size and smaller) up to table-sized laser systems on the transmitting side, but also diverse partly broadband single-pixel and multipixel camera systems for the evaluation of millimetre wave radiation.

THz near-field microscopy

Due to their long wavelength, terahertz waves reach their limits when it comes to detecting the smallest structures. Coupling terahertz waves with a near-field microscope makes it possible to increase lateral resolution down to the nanometre range. This is an analogue mode of operation to the atomic force microscope