Recent progress on the electronic structure, defect, and doping properties of Ga2O3

Abstract

Gallium oxide (Ga2O3) is an emerging wide bandgap semiconductor that has attracted a large amount of interest due to its ultra-large bandgap of 4.8 eV, a high breakdown field of 8 MV/cm, and high thermal stability. These properties enable Ga2O3 a promising material for a large range of applications, such as high power electronic devices and solar-blind ultraviolet (UV) photodetectors. In the past few years, a significant process has been made for the growth of high-quality bulk crystals and thin films and device optimizations for power electronics and solar blind UV detection. However, many challenges remain, including the difficulty in p-type doping, a large density of unintentional electron carriers and defects/impurities, and issues with the device process (contact, dielectrics, and surface passivation), and so on. The purpose of this article is to provide a timely review on the fundamental understanding of the semiconductor physics and chemistry of Ga2O3 in terms of electronic band structures, optical properties, and chemistry of defects and impurity doping. Recent progress and perspectives on epitaxial thin film growth, chemical and physical properties of defects and impurities, p-type doping, and ternary alloys with In2O3 and Al2O3 will be discussed.

Defects in complex oxide thin films for electronics and energy applications: challenges and opportunities

“…Wide bandgap oxide semiconductors are widely utilized in the field of flat-panel displays (FPDs), sensing devices and power electronics due to their fascinating opto-electrical properties, compositional diversities, structural stability and adjustable bandgap values. 43,[298][299][300][301] Motivated by the great promises of oxide semiconductors and devices, great efforts have been made to modulate their performances from different angles including mobility, carrier type (electron or hole), crystallinity, transparency, etc. Defect engineering has been one of the core strategies in controlling oxide semiconductor properties.…”

Ga2O3polymorphs: tailoring the epitaxial growth conditions

“…Heterostructures based on these alloys could dramatically expand the possibilities for the design of novel devices. However, while the technology for b-Ga 2 O 3 ternary alloys is quite advanced and it was already discussed in several papers and books, 1,36 the literature of aand e-Ga 2 O 3 ternary alloys is still quite limited, making an in-depth discussion on this topic premature and beyond the scope of this review. The last remark concerns the actual thermal stability of the a and e polymorphs.…”

Epitaxial Growth of κ‐(AlxGa1−x)2O3 Layers and Superlattice Heterostructures up to x = 0.48 on Highly Conductive Al‐Doped ZnO Thin‐Film Templates by Pulsed Laser Deposition

“…This is substantiated by a tremendous amount of research papers on different phases of Ga 2 O 3 that emerged into a large number of recent reviews. [ 1–5 ] Lately, metastable polymorphs of Ga 2 O 3 came into the focus of research. Especially the orthorhombic κ ‐modification (also referred to as ε ‐Ga 2 O 3 ) is of large interest as it is the only known polymorph predicted to exhibit a spontaneous electrical polarization of ≈23 μC cm −2 along its c ‐direction.…”