Researchers from the Institute of Materials Research and Engineering (IMRE) in Singapore, led by Duc V. Dinh, have recently published a study in the journal Applied Physics Letters, exploring the electrical properties of chromium nitride (CrN) thin films. The team, which includes Jens Herfort, Andreas Fiedler, and Oliver Brandt, has investigated the carrier transport and electrical bandgap of CrN layers, potentially paving the way for new applications in the energy sector.
The researchers grew CrN layers on aluminum nitride (AlN) templates using a technique called plasma-assisted molecular beam epitaxy. They found that the CrN layers exhibited different surface orientations depending on the AlN template used. Both types of layers showed antiferromagnetic properties, with a Néel temperature of around 280 K, meaning they exhibit antiferromagnetism up to this temperature. This property could be useful in spintronic devices, which use the spin of electrons to carry information, potentially leading to more efficient data processing and storage.
The study also revealed that the CrN layers displayed n-type semiconducting behavior across a wide temperature range, from 4 to 920 K. This means that the material could be used in high-temperature electronic devices, such as sensors or power electronics, where traditional silicon-based devices may struggle to perform. The researchers observed two distinct conduction channels at low temperatures: one from a metallic impurity band and the other from the conduction band. This dual-channel conduction could be harnessed to create more complex electronic devices with multiple functionalities.
The temperature dependence of the carrier mobility in the CrN layers was found to be consistent with a nondegenerate semiconductor. Below 400 K, the mobility was governed by ionized-impurity scattering, while above 400 K, phonon scattering took over. This understanding of the scattering mechanisms could help engineers design CrN-based devices with optimized performance. Furthermore, the analysis of the temperature-dependent carrier density revealed two activation energies associated with intrinsic conduction: 0.15 eV, attributed to the fundamental bandgap, and 0.50 eV, representing a higher energy transition. These findings could guide the development of CrN-based electronic and optoelectronic devices, such as transistors and light-emitting diodes.
In summary, this research highlights the potential of CrN as a high-temperature semiconductor with unique magnetic properties. As the energy industry seeks to develop more efficient and robust devices for power generation, transmission, and storage, materials like CrN could play a crucial role in enabling these advancements. The practical applications of this research could extend to various energy sector technologies, including power electronics, sensors, and spintronic devices, contributing to a more sustainable and efficient energy infrastructure.
Source: Duc V. Dinh, Jens Herfort, Andreas Fiedler, and Oliver Brandt, “Carrier transport and electrical bandgaps in epitaxial CrN layers,” Applied Physics Letters (2023).
This article is based on research available at arXiv.