Ultradense and planarized antireflective vertical silicon nanowire array using a bottom-up technique

Ludovic Dupré,Thérèse Gorisse,Angélique Letrouit Lebranchu,Hubert Renevier,Thomas Bernardin,Pascal Gentile,Denis Buttard

doi:10.1186/1556-276x-8-123

Abstract

The production and characterization of ultradense, planarized, and organized silicon nanowire arrays with good crystalline and optical properties are reported. First, alumina templates are used to grow silicon nanowires whose height, diameter, and density are easily controlled by adjusting the structural parameters of the template. Then, post-processing using standard microelectronic techniques enables the production of high-density silicon nanowire matrices featuring a remarkably flat overall surface. Different geometries are then possible for various applications. Structural analysis using synchrotron X-ray diffraction reveals the good crystallinity of the nanowires and their long-range periodicity resulting from their high-density organization. Transmission electron microscopy also shows that the nanowires can grow on nonpreferential substrate, enabling the use of this technique with universal substrates. The good geometry control of the array also results in a strong optical absorption which is interesting for their use in nanowire-based optical sensors or similar devices.

Highlights

Semiconductor nanowires are widely implemented as active elements in devices for various applications such as energy harvesting [1,2], microelectronics [3], or sensors [4,5]
We describe a new bottom-up method to produce silicon nanowire arrays which present a very high density and height homogeneity
We show that a combination of ultrasonic agitation, gold-chemical etching, and silicon plasma etching enables the achievement of high-density arrays of silicon nanowires with a very good length control and homogeneity on a silicon substrate

Summary

Background

Semiconductor nanowires are widely implemented as active elements in devices for various applications such as energy harvesting [1,2], microelectronics [3], or sensors [4,5]. In order to achieve high performances, high densities of nanowires are required to increase efficiency or sensitivity of devices [6,7]. In this purpose, top-down etching of a semiconductor wafer is the most commonly used technique [7,8,9]. It is usually admitted that in this case, growth has to be stopped before the nanowires reach the surface of the AAO template It prevents any structural anomalies such as kinks and increases of the nanowires’ diameter due to the catalyst getting out of the template. The nanowires have a good crystalline quality, and the array features good antireflective properties that could be useful for their implementations in devices such as detectors

Methods

Results and discussion

Conclusions