Facile fabrication of eutectic gallium-indium alloy nanostructure and application in photodetection

Abstract

Eutectic gallium-indium (EGaIn) alloy is a kind of liquid metal and has attracted much attention due to good properties. In order to satisfy the trend of miniaturization and realize more practical applications, the exploration for preparation method and properties of EGaIn at nanoscale are very important. Here, facile vacuum thermal evaporation method is developed to fabricate EGaIn nanostructures. The EGaIn nanoparticle and nanofilm with naturally formed 5 nm thick oxide layers are well prepared. The oxide film formed on the EGaIn surface is an important factor, making the properties of the nanostructure different from the properties of the bulk. Compared with ignorance of oxide layer in bulk materials, the proportion of oxide layer increases evidently in nanostructures, which produce obvious influence on the electric and optical properties. The rectifying characteristic and optoelectronic performance are experimentally observed. The EGaIn nanostructures can generate evident photocurrent responses with good responsivities (∼1 mA W −1 ) and response speed (∼1 s) under irradiation of 206 nm, 405 nm, 532 nm, 635 nm, 808 nm, 1064 nm and 10.6 μm lasers. These properties are completely different from the metallic properties of EGaIn bulk material.

Oxidized eutectic gallium–indium (EGaIn) nanoparticles for broadband light response in a graphene-based photodetector

“…Thus the EGaIn nanostructures with a gradient of chemical composition from outside to inside can be naturally formed. Our previous work 39 based on EGaIn nanofilm has confirmed its wide-band absorption capacity. The existing results 40 show that the small size is more conducive to the formation of oxide film and enhance its effect.…”

“…We analysis that the reasons may be as follows. First, along with the gradient change of oxygen element (from the outmost Ga 2 O 3 layer to the innermost liquid metal), the energy band of nanoparticle would change with depth to achieve the smooth transition of energy band from the big band gap (Ga 2 O 3 ) to the bandgap of zero (metal), 39 which is similar to ZnO nanostructure with changing oxygen content in the direction of axis . 48 Thus, various energy level can be formed on a single nanoparticle.…”

In Situ Active Switching of Bipolar Current Rectification in 2D Semiconductor Vertical Diodes

“…23 In comparison, the amorphous GaO x layer on the surface of EGaIn should be much more conductive due to the ultrathin thickness (∼1 nm) and potentially reduced energy gap, which has been verified in the molecular tunnel junctions showing molecular-lengthdependent tunneling characteristics. 24,25 However, when forming contact with TMDC, the GaO x layer may function as a semiconductor 26 and play an important role in the charge transport across the WSe 2 /EGaIn interface.…”

Recent advances in the fabrication of 2D metal oxides

“…In addition, some metals such as indium (156°C) or tin (231°C) have significantly lower melting points than ordinary metals, which are also considered to be within the category of liquid metals. Moreover, some eutectic alloys with low melting points are also included, such as gallium-based eutectic alloys (EGaIn - eutectic gallium-indium binary alloy [ Wang et al., 2020 ]), galinstan (i.e. gallium-indium-tin ternary alloy), and doped metals (e.g.…”