The Growth of One‐Dimensional Single‐Crystalline AlN Nanostructures by HVPE and Their Field Emission Properties

Abstract

Single-crystalline AlN nanostructures, such as thin films, nanoneedles, nanocolumns, and nanowires, depending on the controlled gas-flow ratio, are synthesized by halide vapor-phase epitaxy (HVPE). In comparison with a typical vapor/ liquid/solid (VLS) mechanism for the growth of nanowires, well-aligned AlN nanorod arrays with diameters below 20 nm are grown on a catalyst-free Si substrate though a vapor/solid (VS) mechanism. Their structural and optical properties are measured by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL). In particular, AlN nanorods exhibit an excellent field emission property with a low turn-on field of 2.25 V mm À1. The field enhancement factor is estimated to be about 784 due to well-aligned, needle-shaped, AlN nanorods.

Synthesis of Patterned AlN Nanoarray and its Photoluminance Property Investigation

“…The as-prepared AlN sample had a low turn-on field of 3.8 Vμm-1 and an intensive light emission at 519nm. Y. K. Byeun et al [11] reported the controlled growth by HVPE of one dimensional single-crystalline AlN nanostructure arrays by employing various controlled growth conditions, such as growth temperature, gas flow rate, and the effects of the use or non-use of catalysts, and they also investigated the field emission properties of these single-crystalline AlN nanostructures, the results showed that the as-grown AlN nanostructures had a low turn-on field and threshold field of 2.25 and 3.58Vmm-1, respectively. However, the randomly distributed AlN nanostructure is not suitable for the final FED anode due to the screening effect, only the highly ordered and orientated AlN nanoarray is the key for production even emission, high lightening, low loss and addressable FED devices.…”

Single-step, catalyst-free plasma-assisted synthesis and growth mechanism of single-crystalline aluminum nitride nanorods

“…1- 6 Here we report on plasma-enabled synthesis of single-crystalline AlN 1D nanorods that combine unique properties specific to bulk AlN and 1D nanomaterials. 3,4 This means that the electrons in the conduction band can escape into the vacuum easily, which can significantly improve the emitting efficiency of AlN-based field emission devices. 7,8 On the other hand, 1D AlN nanostructures with high aspect ratios have very promising applications in field emission devices because of their small and even negative electron affinity.…”

“…A very wide band gap of ϳ6.2 eV, high thermal conductivity and melting point, low and Si-compatible coefficient of thermal expansion, excellent electrical resistance, low dielectric loss, as well as a strong piezoelectric response renders numerous advanced applications of AlN in light-emitting diodes, surface acoustic wave sensors, reinforcement of functional composites, dielectric layers in optical storage media, etc. 3,4 In comparison with conventional micro-and nanosized AlN particles, single-crystalline 1D AlN nanostructures have better electrical, optical, mechanical properties due to their near perfect crystal structure and high aspect ratios. 3,4 This means that the electrons in the conduction band can escape into the vacuum easily, which can significantly improve the emitting efficiency of AlN-based field emission devices.…”

“…3,4 In comparison with conventional micro-and nanosized AlN particles, single-crystalline 1D AlN nanostructures have better electrical, optical, mechanical properties due to their near perfect crystal structure and high aspect ratios. 3,4,[9][10][11] These deposition techniques involve carbothermal reduction of alumina, direct nitridation of aluminum powders, halide vapor-phase epitaxy, direct sublimation of AlN powders, etc. 2 Recently, a broad range of deposition techniques has been developed to synthesize diverse 1D AlN nanostructures ͑including nanorods, nanowires, nanobelts, nanorings, etc.͒ with controllable morphology, size, chemical composition, growth orientation, etc.…”

“…9 In this case, the electron diffusion length can be significantly increased and the electron transport is much faster than percolation through a random poly-or nanocrystalline network. 3,4,[9][10][11] However, most of these processes require very high substrate temperature ͑typically, higher than 900°C͒ and involve the use of metal catalysts ͑typically Au͒. 3,4,[9][10][11] These deposition techniques involve carbothermal reduction of alumina, direct nitridation of aluminum powders, halide vapor-phase epitaxy, direct sublimation of AlN powders, etc.…”