CE08 - Matériaux métalliques et inorganiques et procédés associés

Niobium nitride / III-N heterojunctions grown by molecular beam epitaxy: First demonstration of a metal-based transistor – Niobium

Submission summary

The NIOBIUM project aims at the first realization of a metal-base transistor (MBT) in the III-N semiconductor family. The key point is to develop by epitaxy an original crystalline III-N/metal/III-N heterostructure. The core of the project is the elaboration by molecular beam epitaxy (MBE) of Niobium nitride thin films, the proposed material for the metal base layer. This new generation of high-frequency vertical devices would represent a remarkable breakthrough in the field of GaN radio frequency (RF) devices and would play a major role in the growing demand for connectivity. This breakthrough will be all the more significant as the NIOBIUM project proposes to realize these new MBT devices on silicon substrates.

High electron mobility transistors (HEMTs) on GaN have been studied for more than 20 years. However, their lateral geometry makes it more and more difficult to increase their operation frequency. Vertical transistors overcome several limitations of HEMTs. The reduction of lateral dimensions at high frequency is less drastic, and the device is less sensitive to surface effects.

Although good crystal quality NbN/III-N and III-N/NbN heterostructures have been published in the last few years, most of them obtained by MBE, no III-N/NbN/III-N heterostructure realized by epitaxy has been published to date.

The originality of the project lies mainly in the complementary expertise of III-V Lab, CRHEA and CIMAP. III-V Lab, an industrial research laboratory, has a long history and great expertise in the field of semiconductor components. III-V Lab has recently obtained a patent on metal-based transistors in the III-N semiconductor family. CRHEA brings more than 25 years of expertise in the field of epitaxy of III-N materials. Thanks to the specific know-how of the CRHEA in the epitaxy of III-N on silicon, the growth of NbN containing heterostructures will be optimized on this substrate. The ultimate control of the heterostructures necessary for the demonstration of an MBT transistor will be made possible by a close collaboration with CIMAP, which has the latest technologies and a remarkable expertise in the field of transmission electron microscopy (TEM).

The GaN radio frequency (RF) market is growing rapidly from 630Mn€ in 2019 to 1.7Md€ in 2025 and this seems likely to continue with the arrival of 5G and then 6G. By proposing an innovative transistor with a vertical geometry that allows to reach higher frequencies, while circumventing the locks that limit the performance of HEMTs, the NIOBIUM project offers an opportunity to achieve a remarkable breakthrough in the field of very high frequency components, a strategic area for the technological sovereignty of France and Europe.
Finally, the elaboration by epitaxy of original III-N/NbN heterostructures with an ultimate control of interfaces and thicknesses, where the NbN layer will be metallic at room temperature and superconducting at low temperature, will undoubtedly allow breakthroughs in many other fields where the quality of this type of metal/semiconductor and superconductor/semiconductor heterojunctions plays a key role.

Examples include the study of disorder in the superconducting properties of NbN thin films with applications in the fabrication of high-performance single photon detectors, or the excitation of acoustic waves at the metal/semiconductor piezoelectric interface with applications in the fabrication of bulk acoustic wave resonators.

The development of GaN-based RF components is part of the III-V Lab (Thales-Nokia-CEA-LETI GIE) strategy. Moreover, the links of III-V Lab with UMS (Thales-Airbus JV) allow easier industrial transfers.

Project coordination

Nicolas Michel (III-V Lab)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.


CRHEA Centre de recherche sur l'hétéroepitaxie et ses applications

Help of the ANR 562,928 euros
Beginning and duration of the scientific project: - 42 Months

Useful links

Explorez notre base de projets financés



ANR makes available its datasets on funded projects, click here to find more.

Sign up for the latest news:
Subscribe to our newsletter