Your Partner for Innovative Terahertz Solutions

ACST GmbH (ACST) was founded in April 2006 with the objective of providing the European community with a continuous source of Schottky diodes for mm-wave and THz applications. By founding ACST the first European supplier in this fast-evolving field became available thereby supporting and strengthening the research community and industry.
Being a spin-off company of the Technische Universität Darmstadt (TUD) in Germany, ACST succeeded to over twenty years of technology standards, R&D activity and accumulated experience at TUD in the field of THz technology. This has been used by ACST to build a solid background in fabrication technology of THz Schottky components but also in RF modules and THz systems.
Over the past decade ACST has undertaken over twenty R&D projects supported by ESA, EC (FP7 & H2020), the German Government (BMBF, BMWI) and also leading industrial partners.

Accumulated experience and know-how have successfully been implemented into ACST development strategy and supported ACST to become a leading European source for Schottky-based THz technology targeting at ultimate performance at mm-waves and THz frequencies.
With a strong technology background ACST has been involved in various space projects and currently provides products and technology support for space missions in Europe and Asia.
The ACST business model relies on two core competencies: Component Fabrication Technology and RF-Engineering. These both activities are supporting each-other at ACST, which strongly facilitates development of custom-oriented products and services.

A word from Dr.-Ing. Oleg Cojocari

Even the core of our products − the diode − is rethought and built differently. This makes our products more durable due to more efficient heat dissipation and more sensitive due to improved noise properties. To develop this diode took courage and we had to persevere to achieve the better quality. We have shown pioneering spirit, because we wanted to achieve the maximum performance from the beginning. Today, our THZ sources are the strongest in the world. Due to our company size, we are big enough to be a reliable partner, but small enough to flexibly implement customer wishes.“

Satisfied clients
Years top performance

Component fabrication technology

Relying on its outstanding intellectual property and well-founded technological background ACST has developed a so-called “Film-Diode Process” (FD Process) and structures fabricated by FD-Process are called “Film-Diodes”, which is used for fabrication of III-V semiconductor devices and MMICs on a transferred insulating membrane. The FD process allows for ultra-low parasitics and aims at ultimate performance at mm-wave and THz frequencies.
To address requirements of power electronics, the FD-Process has been modified and the insulating membrane was replaced by monolithically integrated diamond-substrate. This approach allowed increase of power-handling capability of up to 10 times in comparison to traditional diode structures on GaAs substrate. Diode structures fabricated by this process are called “Diamond Diodes”.
Beside new technologies like are Film Diodes and Diamond Diodes ACST is also offering traditional diodes, fabricated by planar technology on s.i. GaAs substrate.
Currently ACST confidently keeps European leadership on supplying Schottky diodes for mm-wave and THz applications.
On system level ACST is the European leading supplier of mm-wave and THz sources.


ACST is defining new performance standards at Module/System level by development of modules and systems based on dedicated components for particular requirements and design solutions.
A particular interest represents ACST high-power multiplier technology. Due to dedicated Schottky components (Diamond Diodes), ACST frequency multipliers can convert unmatched power levels whilst presenting state of the art efficiency and bandwidth.
In-house availability of the entire development chain from microelectronic device fabrication to up/down converter modules and customized systems provides a short development loop. This reduces development time and costs of dedicated solutions for new emerging applications.
ACST dedicated and cost-efficient solutions push THz technology from nice applications into industrial mainstream.


Film-Diode (FD) Process is an ACST originally-developed technology platform for fabrication of discrete devices and integrated circuits for mm/Sub-mm-Wave applications. FD-structures are based on a few-micrometer thin transferred membrane substrate, which maintains integrity of all circuit elements. This approach aims at ultimate performance at mm and Sub-mm-waves.
Various circuit architectures can be accommodated by the FD-process, including discrete diodes and various diode arrays, but also passive circuit elements like are capacitors, resistors, and surrounding circuitry.
Recent FD-based developments include state-of-the-art frequency multipliers up to 600 GHz, frequency mixers up to 660 GHz, RTD-based oscillators up to 1.1THz, and square-low detectors up to 2.5THz.

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