Scientific Concept of the Nitride Semiconductor Research Group

The research group investigates nitride semiconductors across the entire development chain, from controlled synthesis and the mechanistic understanding of crystal growth and defect formation to device concepts based on these materials.

The group’s core methodological pillars comprise ammonothermal crystal growth, in situ monitoring under high-pressure conditions, and numerical modeling.

The goal is to systematically establish the relationships between structure, defects, and functional properties, thereby enabling the targeted development of new materials for applications in electronics and photonics.

Research Focus Areas

Ammonothermal Crystal Growth

Investigation of dissolution, transport, and crystallization under high-pressure conditions with the aim of enabling the controlled growth of high-quality nitride semiconductors with tailored properties.

In Situ Monitoring for Process Understanding

Development and application of technologies for in situ monitoring of ammonothermal processes to elucidate growth dynamics, defect formation, and mass transport, as well as to experimentally validate numerical models.

Defects and Doping Mechanisms

Investigation of the structural and electronic properties of semiconducting nitrides and the targeted control of defects and doping processes, with a particular focus on ammonothermal crystal growth.

Numerical Modeling

Simulation of temperature and flow fields for the quantitative description and systematic, knowledge-based optimization of process conditions, with the long-term goal of extending the modeling approach to include a coupled description of crystal growth processes.

Integration into Electronic and Photonic Devices

Investigation of functional structures for integration into electronic and photonic devices based on advanced semiconductor materials.

Team

The Emmy Noether Research Group in the High-Pressure Laboratory of the Faculty of Engineering (February 2026).

Group leader

Dr.-Ing. Saskia Schimmel

Doctoral candidates

Scientific employee in the coordination project of the Priority Programme Nitrides4Future

Samuel Faber, M.Sc.


Students

The research projects of the junior research group are regularly complemented by student research projects, including research internships as well as Bachelor’s and Master’s theses. Further information on available, ongoing, and completed student projects at the Chair of Electronic Devices (LEB) is available here.

Wissenschaftliche Arbeiten und Aktivitäten

2024

2023

2022

2026

2025

2024

2023

2022

2026

  • PiezoTUNE: Tuning piezo- and ferroelectric properties of III-nitrides by alloying with metal nitrides – crystallization from N2- and NH3-based solutions and gas phases guided by atomistic simulations

    (Third Party Funds Group – Sub project)

    Overall project: SPP 2477: Nitrides4Future – Novel Materials and Device Concepts
    Project leader: ,
    Term: 15. April 2026 - 14. April 2029
    Acronym: PiezoTUNE
    Funding source: DFG / Schwerpunktprogramm (SPP)
    Abstract

    The overarching aim of the present project aims at the tailor-made syntheses and characterization of metal nitrides with enhanced piezoelectric properties. For this, in-depth understanding of III1-xMexN and MeN crystal growth from experiments and atomistic simulations will be provided - both for ammonia- and nitrogen-based gas phases and solutions. The handshaking of molecular simulations and syntheses experiments shall firstly elaborate a profound rationalization of the fundamental mechanisms and aspects of the ferroelectric properties of the resulting products. Based on this atomic-scale understanding we will move towards an increasing rational design of crystal growth to achieve wurtzite III1-xMexN (III=Ga,Al; Me=Cr, B, Y, …) and rocksalt MeN (Me= Y, Sc, …) single crystals of high quality. This involves seed-based growth of multi-layer systems (such as heterostructures in devices), analyses and controlling of defect arrangements and the investigation of elastic and piezoelectric properties offering numerous cooperations with project groups funded by Nitrides4Future priority program.

  • Nitrides4Future: Coordination Funds

    (Third Party Funds Single)

    Project leader:
    Term: 1. May 2026 - 30. April 2029
    Acronym: Nitrides4Future
    Funding source: DFG / Schwerpunktprogramm (SPP)
    URL: https://www.nitrides4future.research.fau.eu/
    Abstract

    Semiconductors are the backbone of modern microelectronics – a key technology for driving innovations. Besides silicon, gallium nitride has been established as reliable platform. The high potential of the material class of nitrides stems from the extraordinarily broad spectrum of material properties: semiconducting, metallic, piezoelectric, ferroelectric or superconducting. Nitride semiconductors are already used commercially in photonic devices such as LEDs and laser diodes as well as in high-frequency and power electronic devices. However, this should not obscure the fact that further development of nitride technology is still strongly limited by the properties of the materials mostly investigated so far. For instance, the efficiency of UVC LEDs is still very low because the defect densities typical of nitrides have a much stronger effect in UVC LEDs than in blue LEDs. For power electronic devices, approaches for realizing vertical device architectures for higher breakdown voltage, higher currents, or normally-off transistors are being studied. However, piezoelectric and ferroelectric properties of some of the new metal nitrides have not been applied at all in device architectures. This could be a very exciting approach, e.g. for the realization of ferroelectric memories and in combination with photonic devices for optical neuromorphic computing. Furthermore, they have enormous potential as piezoelectric acoustic filters in communication electronics. There is also growing evidence that several ternary metal nitrides (beyond the best known representative AlScN) possess highest electro-optic coefficients. Such materials are being considered as promising substitutes for LiNbO3 and could pave the way for a future technology for fabricating photonic circuits for the blue/UV spectral region. Each of the described functionalities are attractive in their own right. However, the combination of the functionalities in one device holds particularly great potential for a disruptive evolution of nitride technology. The potential combination of photonic, electronic, ferroelectric, and electro-optic properties in a single material family is unique. The goal of the priority program is to explore and systematically improve the properties of novel nitrides (such as alloys of AlN with CrN, YN, LaN, YbN, and MoN), and to subsequently realize device architectures that exploit the multitude of functionalities.

  • „Novel nitride materials for electronic devices“ (2. Period of funding)

    (Third Party Funds Single)

    Project leader:
    Term: 1. August 2026 - 31. July 2029
    Funding source: DFG-Einzelförderung / Emmy-Noether-Programm (EIN-ENP)
    Abstract

    The overall goal of the project is to develop selected emerging nitride semiconductors alongside with an improved and more generalizable understanding of ammonothermal growth of nitrides. The project evaluates the fundamental properties of selected emerging ternary nitrides with regard to prospective applications in electronic devices. Bulk crystals will be grown via the ammonothermal method. Alongside with gaining access to the materials, a deepened understanding of the ammonothermal synthesis and doping of binary and ternary materials will be established. The targeted nitrides are suitable for heteroepitaxial integration with each other, which prospectively enables novel combinations of materials properties in electronic devices. Building on previous results on GaN, the material system GaN-AlN-AlGaN will first be investigated. AlGaN will serve as an exemplary case for studying ways of controlled crystallization of ternary nitrides via solute transport in ammonothermal solutions. Methods of intentional doping and conductivity control during ammonothermal crystal growth will be investigated using AlN as an example. The low growth temperatures enabled by ammonothermal synthesis represent a prospective pathway to conductive AlN substrates via doping with Si, which could enable significant improvements in the energy efficiency of vertical power electronic devices. The use of custom high-pressure optical cells creates unique capabilities for monitoring ammonothermal reactions in situ. In the case of Ga, these will be utilized to deepen the fundamental understanding. In situ monitoring will also be applied for expanding the fundamental understanding to the constituent elements of the ternary nitrides targeted in the project, specifically Al, Si, Mg, Mn and Zn. In parallel, in situ monitoring methods for investigating complex systems will be developed further, namely simultaneous in situ measurements with complementary techniques such as x-ray absorption, UV-Vis- and Raman spectroscopy. In addition, the roles of pressure and ammonia density for crystallization will be clarified and the feasibility of crystallization at significantly lower pressures will be evaluated. Within the project, the obtained understanding of the crystallization of ternary nitrides and their transport in ammonothermal fluids will be utilized for the crystallization of three emerging ternary nitride materials of the composition II-Si-N2 (II = Mg, Mn, Zn). Their synthesis as single crystals of good structural quality enables the experimental evaluation of their bulk properties. Building on the obtained knowledge of the properties of these materials, their application prospects in electronic devices will be evaluated further, including a first evaluation of the application potential of epitaxial heterostructures of the investigated materials.

2024

  • KI-FUNKEN: KI-Fähigkeiten für Elektroingenieur*innen: Entfachen von KI-unterstützter Innovation

    (FAU Funds)

    Project leader: ,
    Term: 1. October 2024 - 30. September 2025
    Acronym: KI-FUNKEN

2023

  • High-energy computed tomography for in situ observation of processes taking place inside high-pressure vessels - development using the example of ammonothermal crystal growth of GaN

    (FAU Funds)

    Project leader:
    Term: 15. January 2023 - 14. January 2024

  • „Novel nitride materials for electronic devices“ (1st period of funding)

    (Third Party Funds Single)

    Project leader:
    Term: 1. August 2023 - 30. September 2027
    Funding source: DFG-Einzelförderung / Emmy-Noether-Programm (EIN-ENP)
    Abstract

    The overall goal of the project is to develop selected emerging nitride semiconductors alongside with an improved and more generalizable understanding of ammonothermal growth of nitrides. The project evaluates the fundamental properties of selected emerging ternary nitrides with regard to prospective applications in electronic devices. Bulk crystals will be grown via the ammonothermal method. Alongside with gaining access to the materials, a deepened understanding of the ammonothermal synthesis and doping of binary and ternary materials will be established. The targeted nitrides are suitable for heteroepitaxial integration with each other, which prospectively enables novel combinations of materials properties in electronic devices. Building on previous results on GaN, the material system GaN-AlN-AlGaN will first be investigated. AlGaN will serve as an exemplary case for studying ways of controlled crystallization of ternary nitrides via solute transport in ammonothermal solutions. Methods of intentional doping and conductivity control during ammonothermal crystal growth will be investigated using AlN as an example. The low growth temperatures enabled by ammonothermal synthesis represent a prospective pathway to conductive AlN substrates via doping with Si, which could enable significant improvements in the energy efficiency of vertical power electronic devices. The use of custom high-pressure optical cells creates unique capabilities for monitoring ammonothermal reactions in situ. In the case of Ga, these will be utilized to deepen the fundamental understanding. In situ monitoring will also be applied for expanding the fundamental understanding to the constituent elements of the ternary nitrides targeted in the project, specifically Al, Si, Mg, Mn and Zn. In parallel, in situ monitoring methods for investigating complex systems will be developed further, namely simultaneous in situ measurements with complementary techniques such as x-ray absorption, UV-Vis- and Raman spectroscopy. In addition, the roles of pressure and ammonia density for crystallization will be clarified and the feasibility of crystallization at significantly lower pressures will be evaluated. Within the project, the obtained understanding of the crystallization of ternary nitrides and their transport in ammonothermal fluids will be utilized for the crystallization of three emerging ternary nitride materials of the composition II-Si-N2 (II = Mg, Mn, Zn). Their synthesis as single crystals of good structural quality enables the experimental evaluation of their bulk properties. Building on the obtained knowledge of the properties of these materials, their application prospects in electronic devices will be evaluated further, including a first evaluation of the application potential of epitaxial heterostructures of the investigated materials.