Nitride Semiconductors

The compound semiconductors indium, gallium and aluminum nitride and their alloys are the second most economically important class of semiconductors after silicon. For example, they form the basis of light-emitting diodes (LEDs) that have revolutionized the general lighting market in the past decade and for amplifiers and electronic switches in power electronics. The high efficiency of these components is an important factor for reducing the consumption of electrical energy.

PDI has a longstanding tradition in both producing high-quality epilayers of nitride semiconductors by molecular beam epitaxy and their detailed characterization, in particular using luminescence spectroscopy. Currently, we are pursuing three complementary research directions in this context, with a particular focus on materials with an ultra-wide band gap. Firstly, we are working on innovative electronic components based on high electron mobility transistors (HEMTs) utilizing aluminum nitride. Secondly, we explore the growth of novel nitride compounds. Alloys with transition metals such as scandium or chromium can enable new functionalities such as ferroelectricity and ferromagnetism. Boron nitride is highly relevant in heterostructures with two-dimensional materials, but also as potential host for room-temperature quantum emitters. Thirdly, we are investigating charge carrier recombination with the aim to understand basic material properties and to identify ways to improve optoelectronic components. In this context, the new application laboratory for time-resolved cathodoluminescence spectroscopy (ZALKAL) plays a central role as it is specially designed for semiconductors with an ultra-wide band gap.

• Electrical properties of ScN(111) layers grown on semi-insulating GaN(0001) by plasma-assisted molecular beam epitaxy; D. V. Dinh, O. Brandt; Journal: Phys. Rev. Appl. 22, 014067 (2024)
• Generation of GHz surface acoustic waves in (Sc,Al)N thin films grown on free-standing polycrystalline diamond wafers by plasma-assisted molecular beam epitaxy; M. Yuan, D. V. Dinh, S. Mandal, O. A. Williams, Z. Chen, O. Brandt, P. V. Santos; J. Phys. D: Appl. Phys., 57, 495103 (2024)

• Application laboratory time-resolved cathodoluminescence spectroscopy (ZALKAL)
• Defect-engineering in graphene via focused ion beam for tailored van der Waals epitaxy of h-BN (ENGRAVE)
• Complementary Electron Microscopy Techniques for Efficient AlGaN Optoelectronics (DAAD Procope, with Institut Néel)

2025

1. Growth of compositionally uniform InxGa1−xN layers with low relaxation degree on GaN by molecular beam epitaxy
   Authors: J. Kang, M. Gómez Ruiz, D. V. Dinh, A. Campbell, P. John, T. Auzelle, A. Trampert, J. Lähnemann, O. Brandt, L. Geelhaar
   Source: J. Phys. D: Appl. Phys., 58, 14LT01 (2025)
   DOI: 10.1088/1361-6463/adb4e7

2024

1. Electrical properties of ScN(111) layers grown on semi-insulating GaN(0001) by plasma-assisted molecular beam epitaxy
   Authors: D. V. Dinh, O. Brandt
   Source: Phys. Rev. Appl., 22, 014067 (2024)
   DOI: 10.1103/PhysRevApplied.22.014067
    
2. Generation of GHz surface acoustic waves in (Sc,Al)N thin films grown on free-standing polycrystalline diamond wafers by plasma-assisted molecular beam epitaxy
   Authors: M. Yuan, D. V. Dinh, S. Mandal, O. A. Williams, Z. Chen, O. Brandt, P. V. Santos
   Source: J. Phys. D: Appl. Phys., 57, 495103 (2024)
   DOI: 10.1088/1361-6463/ad76ba
    
3. Multimode emission in GaN microdisk lasers
   Authors: M. L. Drechsler, L. Sung-Min Choi, F. Tabataba-Vakili, F. Nippert, A. Koulas-Simos, M. Lorke, S. Reitzenstein, B. Alloing, P. Boucaud, M. R. Wagner, F. Jahnke
   Source: Laser Photonics Rev., 18, 2400221 (2024)
   DOI: 10.1002/lpor.202400221

2023

1. Excitonic and deep-level emission from N- and Al-polar homoepitaxial AlN grown by molecular beam epitaxy
   Authors: L. van Deurzen, J. Singhal, J. Encomendero, N. Pieczulewski, C. S. Chang, Y. Cho, D. A. Muller, H. G. Xing, D. Jena, O. Brandt, J. Lähnemann
   Source: APL Mater., 11, 081109 (2023)
   DOI:10.1063/5.0158390
    
2. Lattice parameters of ScxAl1−xN layers grown on GaN(0001) by plasma-assisted molecular beam epitaxy
   Authors: D. V. Dinh, J. Lähnemann, L. Geelhaar, O. Brandt
   Source: Appl. Phys. Lett., 112, 152103-1 (2023)
   DOI: 10.1063/5.0137873