Electronic Properties of Group-III Nitride Semiconductors and Device Structures Probed by THz Optical Hall

Authors

Nerijus Armakavicius, Linköping University
Philipp Kühne, Linköping University
Alexis Papamichail, Linköping University
Hengfang Zhang, Linköping University
Sean Knight, Linköping University
Axel Persson, Linköping University
Vallery Stanishev, Linköping University
Jr-Tai Chen, Linköping University, SweGaN AB
Plamen Paskov, Linköping University
Mathias Schubert, Linköping University, University of Nebraska - LincolnFollow
Vanya Darakchieva, Linköping University, Lund University

Document Type

Article

Date of this Version

6-27-2024

Citation

Armakavicius, N.; Kühne, P.; Papamichail, A.; Zhang, H.; Knight, S.; Persson, A.; Stanishev, V.; Chen, J.-T.; Paskov, P.; Schubert, M.; et al. Electronic Properties of Group-III Nitride Semiconductors and Device Structures Probed by THz Optical Hall Effect. Materials 2024, 17, 3343. https://doi.org/10.3390/ ma17133343

Comments

Open access.

Abstract

Group-III nitrides have transformed solid-state lighting and are strategically positioned to revolutionize high-power and high-frequency electronics. To drive this development forward, a deep understanding of fundamental material properties, such as charge carrier behavior, is essential and can also unveil new and unforeseen applications. This underscores the necessity for novel characterization tools to study group-III nitride materials and devices. The optical Hall effect (OHE) emerges as a contactless method for exploring the transport and electronic properties of semiconductor materials, simultaneously offering insights into their dielectric function. This nondestructive technique employs spectroscopic ellipsometry at long wavelengths in the presence of a magnetic field and provides quantitative information on the charge carrier density, sign, mobility, and effective mass of individual layers in multilayer structures and bulk materials. In this paper, we explore the use of terahertz (THz) OHE to study the charge carrier properties in group-III nitride heterostructures and bulk material. Examples include graded AlGaN channel high-electron-mobility transistor (HEMT) structures for high-linearity devices, highlighting the different grading profiles and their impact on the two-dimensional electron gas (2DEG) properties. Next, we demonstrate the sensitivity of the THz OHE to distinguish the 2DEG anisotropic mobility parameters in N-polar GaN/AlGaN HEMTs and show that this anisotropy is induced by the step-like surface morphology. Finally, we present the temperature-dependent results on the charge carrier properties of 2DEG and bulk electrons in GaN with a focus on the effective mass parameter and review the effective mass parameters reported in the literature. These studies showcase the capabilities of the THz OHE for advancing the understanding and development of group-III materials and devices.