Vacancy Defects in Ga2O3: First-Principles Calculations of Electronic Structure

Abstract

First-principles density functional theory (DFT) is employed to study the electronic structure of oxygen and gallium vacancies in monoclinic bulk β-Ga2O3 crystals. Hybrid exchange–correlation functional B3LYP within the density functional theory and supercell approach were successfully used to simulate isolated point defects in β-Ga2O3. Based on the results of our calculations, we predict that an oxygen vacancy in β-Ga2O3 is a deep donor defect which cannot be an effective source of electrons and, thus, is not responsible for n-type conductivity in β-Ga2O3. On the other hand, all types of charge states of gallium vacancies are sufficiently deep acceptors with transition levels more than 1.5 eV above the valence band of the crystal. Due to high formation energy of above 10 eV, they cannot be considered as a source of p-type conductivity in β-Ga2O3.

Recent progress on the effects of impurities and defects on the properties of Ga2O3

“…Zacherle et al found the related phenomena. 143,169–171 Although V O s were easily formed at the low oxygen partial pressure, the transition level from the neutral state to the +2 state was the deep level in the bandgap whether in the O-rich or O-poor ambient condition, as shown in Fig. 10(c and d).…”

“…, E c − E (0/+2) > 1 eV), which had also been obtained in other literature. 171–173 This indicated that the V O was a deep-level defect. Moreover, Onuma et al found that the blue emission was observed in β-Ga 2 O 3 , which was attributed to the recombination between the deep local donor and the trapped hole.…”

The Effect of Gate Work Function and Electrode Gap on Wide Band-Gap Sn-Doped α-Ga2O3 Metal–Semiconductor Field-Effect Transistors

“…Among five different phases of Ga 2 O 3 (α, β, γ, ε, and δ) [ 3 ], the orthorhombic β phase is the most stable thermodynamically, while the rhombohedral corundum α phase is semi-stable [ 4 ]. On the other hand, the band gap of α-Ga 2 O 3 is 5.3 eV [ 5 , 6 ], which is wider compared to β-Ga 2 O 3 4.9 eV [ 1 , 7 , 8 ], promising a higher breakdown field.…”

P-type Inversion at the Surface of β-Ga2O3 Epitaxial Layer Modified with Au Nanoparticles

“…Opinions on the source of n-type conductivity are divided. The literature attributes it to unintentional dopants (introduced during the process of synthesis) as well as the presence of various types of defects in the crystal structure of this material: oxygen vacancies, hydrogen interstitials and substitutions, and Ga interstitials [2,15,16]. Experimental studies show that the resistivity of the crystalline grains' boundaries, but also their bulk, increases with the concentration of oxygen in the ambient atmosphere [17].…”