Catalyst-Assisted Large-Area Growth of Single-Crystal β-Ga2O3 Nanowires on Sapphire Substrates by Metal–Organic Chemical Vapor Deposition

Abstract

In this work, we have achieved synthesizing large-area high-density β-Ga2O3 nanowires on c-plane sapphire substrate by metal–organic chemical vapor deposition assisted with Au nanocrystal seeds as catalysts. These nanowires exhibit one-dimensional structures with Au nanoparticles on the top of the nanowires with lengths exceeding 6 μm and diameters ranging from ~50 to ~200 nm. The β-Ga2O3 nanowires consist of a single-crystal monoclinic structure, which exhibits strong ( 2 ¯ 01) orientation, confirmed by transmission electronic microscopy and X-ray diffraction analysis. The PL spectrum obtained from these β-Ga2O3 nanowires exhibits strong emissions centered at ~360 and ~410 nm, respectively. The energy band gap of the β-Ga2O3 nanowires is estimated to be ~4.7 eV based on an optical transmission test. A possible mechanism for the growth of β-Ga2O3 nanowires is also presented.

β-Ga2O3 Air-Channel Field-Emission Nanodiode with Ultrahigh Current Density and Low Turn-On Voltage

“…Specifically, calculated Φ decreases from 5.9 eV at 77 K to 4.5 eV at 350 K. The work function of n -doped β-Ga 2 O 3 at room temperature in previous reports varies from 4.6 to 5.2 eV; , however, to the best of our knowledge, the work functions of β-Ga 2 O 3 at different temperatures have not been reported yet. The electron affinity χ of β-Ga 2 O 3 is ∼4 eV, and the band gap E g of β-Ga 2 O 3 NW is ∼4.7 eV according to our previous work . According to the theoretical calculation considering the influence of temperature on χ and E g , the reasonable range of Φ for n -doped β-Ga 2 O 3 is from 4 to 6.35 eV at different temperatures (see Supplementary VI), which is in good agreement with our measurement and calculation results.…”

“…The electron affinity χ of β-Ga 2 O 3 is ∼4 eV, 36 and the band gap E g of β-Ga 2 O 3 NW is ∼4.7 eV according to our previous work. 24 According to the theoretical calculation considering the influence of temperature on χ and E g , the reasonable range of Φ for n-doped β-Ga 2 O 3 is from 4 to 6.35 eV at different temperatures (see Supplementary VI), which is in good agreement with our measurement and calculation results. The enhancement factor β increases from ∼1650 to ∼2300 as the temperature increased from 77 to 300 K, which is consistent with the results reported in previous works.…”

“…In the zoom-in TEM image shown in Figure 1d, the d-spacing of ∼0.29 nm corresponds to the (004) lattice plane of the β-Ga 2 O 3 with the growth direction of (−201). 24 Raman analysis confirms that the NWs grown in this work are β-phase with good crystal quality (see Supplementary II).…”

Morphology of Ga2O3 Nanowires and Their Sensitivity to Volatile Organic Compounds

“…Among others, the following additive methods are used to synthesize β-Ga 2 O 3 nanowires: thermal method [ 32 ]; chemical vapor deposition (CVD) [ 33 ]; metal-organic chemical vapor deposition (MOCVD) [ 34 ]. …”

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

“…Gold nanoparticles are commonly used as a growth catalyst of β-Ga 2 O 3 fibrous nanostructures (e.g., nanowires), where they remain anchored at the top of the growing structures [27][28][29][30]. However, Lu et al [31] have researched the photocatalytic activity of β-Ga 2 O 3 nanowires surface-decorated with 4-8 nm Au nanoparticles with a distribution density of approximately 420/µm 2 .…”