【International Papers】β-Ga₂O₃-Based Heterostructures and Heterojunctions for Power Electronics: A Review of the Recent Advances

      Researchers from the Arizona State University have published a dissertation titled "β-Ga₂O₃-Based Heterostructures and Heterojunctions for Power Electronics: A Review of the Recent Advances " in Electronics.

Abstract

      During the past decade, Gallium Oxide (Ga₂O₃) has attracted intensive research interest as an ultra-wide-bandgap (UWBG) semiconductor due to its unique characteristics, such as a large bandgap of 4.5–4.9 eV, a high critical electric field of ~8 MV/cm, and a high Baliga’s figure of merit (BFOM). Unipolar β-Ga₂O₃ devices such as Schottky barrier diodes (SBDs) and field-effect transistors (FETs) have been demonstrated. Recently, there has been growing attention toward developing β-Ga₂O₃-based heterostructures and heterojunctions, which is mainly driven by the lack of p-type doping and the exploration of multidimensional device architectures to enhance power electronics’ performance. This paper will review the most recent advances in β-Ga₂O₃ heterostructures and heterojunctions for power electronics, including NiO_x/β-Ga₂O₃, β-(Al_xGa_1−x)₂O₃/β-Ga₂O₃, and β-Ga₂O₃ heterojunctions/heterostructures with other wide- and ultra-wide-bandgap materials and the integration of two-dimensional (2D) materials with β-Ga₂O₃. Discussions of the deposition, fabrication, and operating principles of these heterostructures and heterojunctions and the associated device performance will be provided. This comprehensive review will serve as a critical reference for researchers engaged in materials science, wide- and ultra-wide-bandgap semiconductors, and power electronics and benefits the future study and development of β-Ga₂O₃-based heterostructures and heterojunctions and associated power electronics.

Figure 1. (a) Band alignment of NiO_x/β-Ga₂O₃ with annealing at varying temperatures (up to 600 °C). (b) X-ray photoelectron spectroscopy (XPS) spectra illustrating the composition of deposited NiO_x. (c) X-ray diffraction (XRD) pattern of NiO_x at different annealing temperatures. (d) Variation in O/Ni and Ni₂O₃/NiO ratios and (e) variation in bandgap and resistivity achieved by changing the O₂/Ar gas flow. (f) Variation in bandgap and Ni₂O₃/NiO ratio with annealing temperature.

Figure 2. (a) Band alignment and interface recombination at low bias (<~1.5 V) and (b) multi-step tunneling at high bias (>1.5 V) in a NiO_x/β-Ga₂O₃ p-n diode. (c) Transmission electron microscope (TEM) image of a fabricated p-n diode encompassing all regions. (d) The p-n diode interface with a sputtered NiO_x layer, with the blue arrow indicating some interface deformation due to the involvement of high-energy plasma (150 W). (e) Low-power sputtered heterojunction with minimal damage to the interface (70 W). (f) E-beam-deposited p-n diode featuring an abrupt interface.

Paper Link：https://doi.org/10.3390/electronics13071234