Morphological Control of Single‐Crystalline Silicon Nanowire Arrays near Room Temperature

Abstract

Control of the orientation, diameter, and length of silicon nanowires (SiNWs) is achieved in large‐scale single‐crystalline SiNW arrays fabricated by a statistical electroless metal deposition technique. Taguchi methods are employed to optimize the diameter control and to understand the influence of all processing factors on the growth. The 〈100〉 directions are found to be the preferred crystallographic orientation of the growing SiNWs (see figure).

Evolution of Etching Kinetics and Directional Transition of Nanowires Formed on Pyramidal Microtextures

“…Dry etching processes, such as reactive ion etching (RIE), inductively coupled plasma RIE, electron cyclotron resonance plasma etching, and others, [5][6][7] normally involve ion/plasma generation as well as chemical dissociation, and vacuum A C H T U N G T R E N N U N G systems are inevitably required. By contrast, wet etching techniques, including acidic etching, strain etching, [8] alkaline etching, [9,10] tetramethylammonium hydroxide (TMAH) etching, [11] and metal-assisted chemical etching (MACE), [12][13][14][15] are associated with the chemical or electrochemical dis-A C H T U N G T R E N N U N G solution of Si in aqueous solution. These methods eliminate the need for conventional vacuum systems and thus facilitate a low-cost Si texturization through mass production.…”

“…[9][10][11] Recently, MACE has been extensively studied because it promises an inexpensive, simple, and rapid fabrication of one-dimensional nanostructures. [12][13][14][15] Moreover, this method incorporated into the conventional lithographic process further allows the design of three-dimensional structures with controllable topographical geometries, particularly benefiting micromachining and biomedical applications. [16,17] Still, for the practical implementation of MACE, a systematic understanding of etching kinetics remains a prerequisite and only few deliberations have been given to address these issues so far.…”

Fabrication of ultrahigh aspect ratio silicon nanostructures using self-assembled gold metal-assisted chemical etching

“…5,12 Furthermore, it should also be noted that previous studies have generally been limited to metal patterns that are significantly larger than the patterns we have examined. [5][6][7][8][9]12,13,[16][17][18] To test the impact of solution ratio, we performed the etch at six different ratios (by volume): 6∶1, 3∶1, 2∶1, 3∶2, 1∶1, and 1∶2 HF∶H 2 O 2 for 1 min. This grouping of ratios straddles what was reported by Chartier et al 4 to be the optimal concentration of 80% HF to 20% H 2 O 2 by mol corresponding to a volumetric ratio of nearly 3∶2 for maximum metal penetration rate.…”

“…4,5,7,8,[13][14][15] With self-assembly, it is possible to reach geometrical features far smaller than what can be realized by lithographic patterning. The most common self-assembly approach uses a metal salt bath, such as AgNO 3 , 8,9,14,[16][17][18] where the etch geometry is defined by silver dendrite formation from the solution. While modest control of the dendrite geometry has been demonstrated, 18 the resulting etched features are larger than 50 nm.…”

“…The most common self-assembly approach uses a metal salt bath, such as AgNO 3 , 8,9,14,[16][17][18] where the etch geometry is defined by silver dendrite formation from the solution. While modest control of the dendrite geometry has been demonstrated, 18 the resulting etched features are larger than 50 nm. Generally, features smaller than 10 nm are necessary to observe quantum confinement effects.…”