Efficient White Light Emission from Ga/Ga₂O₃ Hybrid Nanoparticles

Abstract

Noble metals such as gold (Au) and silver (Ag) have been widely used as plasmon materials due to their excellent optical and thermal properties. Although Ag possesses excellent optical properties, it suffers serious oxidation when exposing to air. Au has outstanding chemical stability, however, the large d-s band absorption at high frequencies limits its plasmonic performance in the ultraviolet spectral region. [4] Apart from Ag and Au, gallium (Ga) is now showing great promise because of its unique chemical and physical properties. It has a very low melting point of just 303 K (29 °C) and possesses surface plasmon resonances spanning the ultraviolet to visible spectral region. [5][6][7][8] Additionally, Ga is chemically stable because of the existence of a thin gallium oxide (Ga 2 O 3 ) layer on the surface. Ga nanoparticles (NPs) appear highly promising for surface-enhanced Raman scattering/fluorescence because of their remarkable SPRs. [9][10][11][12] The low melting point of Ga renders it an advantage for making all-optical phase-change memory and logic devices, [13] phase transition nonlinear substrates, [14] and high-capacity self-healing anodes in lithium-ion batteries. [15] Recently, it has been experimentally confirmed through real-time ellipsometry the stable coexistence between solid core and liquid shell in substrate-supported Ga NPs. [16] In addition, Ga has excellent flexibility, stretchability, and low toxicity, which makes it an attractive candidate for flexible electronics and wearable sensing devices. [17] Broadband nanoscale emitters at optical frequencies are now attracting tremendous interest because they are urgently needed for various practical applications, such as ultra-compact optical chips, nanospectroscopy, and active photonic devices. [18,19] Nanoscale white light emitters can be used to probe the near field and to map the local density of states of a nanostructure. However, the achievement of efficient nanoscale white light sources still remains a big challenge. According to Fermi's golden rule, [20,21] the emission intensity of a nanostructure is proportional to the local electric field at the emission wavelength E em (r, λ em ), which is known as the Purcell effect. In addition, it is also closely related to the electric Gallium (Ga) emerges as a promising material in plasmonics mainly due to its extraordinary properties, such as changeable material phase, tunable plasmon resonances across the ultraviolet to near-infrared spectral range, and remarkable chemical stability. Here, the efficient white light emission from gallium oxide (Ga 2 O 3 ) nanoparticles doped with liquid Ga nanodots, which are fabricated by using a laser-induced oxidation method is reported. The quantum efficiency of Ga/Ga 2 O 3 hybrid nanoparticles is found to be ≈1.3%, which is nearly two orders of magnitude larger than that of liquid Ga nanoparticles. It is revealed that the existence of Schottky barrier and hotspots in Ga/Ga 2 O 3 nanoparticles plays a crucial role in enhancing the quantum efficiency. As an ...

Surface Optics and Color Effects of Liquid Metal Materials

“…Furthermore, the Schottky barrier between metal/oxide semiconductors and the presence of hot electrons in Ga/Ga 2 O 3 nanoparticles play a crucial role in enhancing luminescence properties. [136][137][138]…”

Fabrication of β-Ga2O3 Nanotubes via Sacrificial GaSb-Nanowire Templates

“…Ga 2 O 3 nanostructures have attracted intense interest because of their promising applications as functional devices [1][2][3][4][5][6][7][8][9][10][11]. Among them, one-dimensional Ga 2 O 3 nanocrystals including nanowires, nanobelts, nanorods, and nanotubes are demonstrated to be the ideal materials for high-performance electronic devices [12][13][14], sensors [15][16][17], solar-blind photodetectors [16,[18][19][20], and catalyzers [21,22], benefiting from their high surface-to-volume ratios.…”