Growth of Single-Crystalline Wurtzite Aluminum Nitride Nanotips with a Self-Selective Apex Angle

Abstract

Single‐crystalline, hexagonal aluminum nitride nanotips are fabricated using a vapor‐transport and condensation process (VTCP) on silicon substrates with or without a catalyst layer. The resultant tips have very sharp nanoscale apexes (∼1 nm), while their bases and lengths are up to hundreds of nanometers wide and several micrometers long, respectively. It has been demonstrated that the thickness of the gold‐catalyst layer plays a critical role in controlling the size of the tip; in addition, a catalyst‐free growth mode has been observed, which results in lesser control over the nanotip morphology. Nevertheless, a remarkably narrow distribution of the apex angle of the nanotips, regardless of whether or not a catalyst was used in the VTCP, has been obtained. Compared with the commonly observed ridge and pyramid structures, the nanotips produced by VTCP have higher angles (∼81°) between the tilted (221) and the basal (001) planes that encase it. A mechanism for this self‐selective apex angle in aluminum nitride nanotip growth is proposed.

Combustion synthesis of rod-like AlN nanoparticles

“…1),4), 5) 1-D AlN nanostructures (nanofibers, 6) nanowhiskers, 7) nanowires, 8)- 10) nanotubes, 11) nanotips 12) and nanobelts 13) have been synthesized by several methods, including chemical vapor deposition, carbothermal reduction reaction and direct nitridation of Al powders.…”

Aligned AlN Nanorods with Multi‐tipped Surfaces—Growth, Field‐Emission, and Cathodoluminescence Properties

“…As a result, significant effort is being devoted to reducing the tip size and increasing the density of the emitting sites by using hierarchical nanostructures. Therefore, the synthesis of AlN nanostructures, such as nanowires, [3] nanotubes, [4] nanocones, [5] nanotips, [6,7] hierarchical comb-like structures, [8] and nanobelts, [9] with controlled high-aspect-ratio shapes and sizes is an important topic worthy of exploration. The promise that one-dimensional (1D) ), [5] nanotips (3.1-4.7 V lm -1 ), [6,7] and hierarchical comb-like structures (2.45-3.76 V lm -1…”

The Controlled Growth of Long AlN Nanorods and In-situ Investigation on Their Field Emission Properties

“…As explained in the reference, the tight bonding force may exist between the catalyst and the substrate at the beginning of the growth (Fan et al, 1999). The formation mechanism of three morphologies of AlN nanostructures may be attributed to the diffusion mediated growth mechanism (Shi et al, 2005). Based on this model (Shi et al, 2005), AlN precursors have different diffuse length for different growth planes, and these growth planes should have different growth rate at different temperature at the same time.…”

“…The formation mechanism of three morphologies of AlN nanostructures may be attributed to the diffusion mediated growth mechanism (Shi et al, 2005). Based on this model (Shi et al, 2005), AlN precursors have different diffuse length for different growth planes, and these growth planes should have different growth rate at different temperature at the same time. The anisotropy of the growth plane at different temperature will lead to the formation of nanorod or nanocone, i.e., high temperature (>900 o C) benefits for the synthesis of AlN nanorods, as shown in Table 1.…”

“…Among them, AlN nanostructures should deserve paid much attention due to their high melting-point (> 2300 o C), high thermal conductivity (K ~ 320 W/m·k), large exciton binding energy and strong endurance to harsh environment (Davis, 1991;Nicolaescu et al, 1994;Sheppard et al, 1990;Ponthieu et al, 1991). There have emerged many synthesis methods to fabricate different morphology of AlN nanostructures, such as nanocone, nanorod, and nanorods Zhao et al, 2004;Tang et al, 2005;Shi et al, 2005Shi et al, , 2006Wu et al, 2003;Paul et al, 2008). But for actual device applications of AlN nanostructures, there still exist many technique questions, which need to be solved as soon as possible.…”