Novel Nanostructures of Functional Oxides Synthesized by Thermal Evaporation

Abstract

Functional oxides are the fundamentals of smart devices. This article reviews novel nanostructures of functional oxides, including nanobelts, nanowires, nanosheets, and nanodiskettes, that have been synthesized in the authors’ laboratory. Among the group of ZnO, SnO2, In2O3, Ga2O3, CdO, and PbO2, which belong to different crystallographic systems and structures, a generic nanobelt structure has been synthesized. The nanobelts are single crystalline and dislocation‐free, and their surfaces are atomically flat. The oxides are semiconductors, and have been used for fabrication of nanodevices such as field‐effect transistors and gas sensors. Taking SnO2 and SnO as examples, other types of novel nanostructures are illustrated. Their growth, phase transformation, and stability are discussed. The nanobelts and related nanostructures are a unique group that is likely to have important applications in electronic, optical, sensor, and optoelectronic nanodevices.

Enhanced output voltage generation via ZnO nanowires (50 nm): Effect of diameter thinning on voltage enhancement

“…After carbon nanotubes [1][2][3] and silicon nanowires [4][5][6], ZnO nanostructures have attracted researchers due to its wide range of applications in electronics and optoelectronic industry. ZnO is an important semiconductor material having a direct bandgap of 3.34 eV; due to its wide band gap it has got numerous applications in optics, sensors, spintronics, actuators and biomedical sciences [7].…”

Lattice dynamics of a mist-chemical vapor deposition-grown corundum-like Ga2O3 single crystal

“…6 The monoclinic b-phase is thermodynamically the most stable phase at ambient conditions. 7 Owing to its unique physical properties, such as chemical and thermal stability at high temperatures, large bandgap (E g ¼ 4.9 eV), large breakdown field (estimated at 8 MV cm À1 ), and high dielectric constant ($10) 8,9 as well as to its widely tunable conductivity, 10 a great effort has been devoted in the past decade to the development of b-Ga 2 O 3 -based device technology.…”

Generalized self-assembly of scalable two-dimensional transition metal oxide nanosheets

“…For example, the 2D carbon network-graphenefeatures extremely high carrier mobility, mechanical flexibility, optical transparency and chemical stability, which provide a great opportunity for developing new electronic materials, novel sensors and metrology facilities, and superior energy conversion and storage devices [4][5][6] . Although transition metal oxides have been widely studied as functional materials so far, they are mainly obtained in the form of 0D (nanodots and fine nanoparticles), 1D (nanowires and nanotubes) and 3D mesoporous structures and nanoclusters [9][10][11][12] . In contrast, 2D nanomaterials, especially those with confined thickness, have remained conspicuously absent until the recent emergence of delamination of layered compounds into single layers, referred to as exfoliation or top-down synthesis 3,[7][8][13][14][15][16][17][18] .…”