Layer-by-Layer Assembly of Nanowires for Three-Dimensional, Multifunctional Electronics

Abstract

We report a general approach for three-dimensional (3D) multifunctional electronics based on the layer-by-layer assembly of nanowire (NW) building blocks. Using germanium/silicon (Ge/Si) core/shell NWs as a representative example, ten vertically stacked layers of multi-NW fieldeffect transistors (FETs) were fabricated. Transport measurements demonstrate that the Ge/Si NW FETs have reproducible high-performance device characteristics within a given device layer, that the FET characteristics are not affected by sequential stacking, and importantly, that uniform performance is achieved in sequential layers 1 through 10 of the 3D structure. Five-layer single-NW FET structures were also prepared by printing Ge/Si NWs from lower density growth substrates, and transport measurements showed similar high-performance characteristics for the FETs in layers 1 and 5. In addition, 3D multifunctional circuitry was demonstrated on plastic substrates with sequential layers of inverter logical gates and floating gate memory elements. Notably, electrical characterization studies show stable writing and erasing of the NW floating gate memory elements and demonstrate signal inversion with larger than unity gain for frequencies up to at least 50 MHz. The ability to assemble reproducibly sequential layers of distinct types of NW-based devices coupled with the breadth of NW building blocks should enable the assembly of increasing complex multilayer and multifunctional 3D electronics in the future.Over the past several years, semiconductor NWs 1,2 and carbon nanotubes 3 have been actively explored as the potential materials for future electronic components. These chemically derived single-crystalline nanostructures present unique advantages over conventional semiconductors, as they enable integration of high-performance device elements onto virtually any substrate 4-6 with scaled on-currents and switching speeds higher than state-of-the-art planar Si structures. 7,8 These unique electrical properties and the intrinsically miniaturized dimensions of NW and carbon nanotube building blocks may facilitate the continuation of Moore's law and the evolutionary quest for ever faster and smaller electronics well into the future. More uniquely, the capability of assembling high-performance NW building blocks with diverse functional properties could enable novel circuit concepts such as 3D integrated electronics, 9 where 3D structure arises from sequential assembly 10-12 of NWs into vertically stacked device layers.Indeed, there has been considerable interest in multilayer electronics, as they offer a more efficient interconnection and processing of digital information. [13][14][15] However, materials-and fabrication-related challenges have presented major obstacles in achieving truly 3D integrated circuits based on the conventional Si CMOS technology, and the need for a new technology remains critical. Here, we report the monolithic integration of individual and parallel arrays of crystalline NWs as multifunctional and multilayer circuits...

Design of Nanowire Optical Cavities as Efficient Photon Absorbers

“…These observations shed light on implementation of large area arrays of NW PVs for next generation solar cells. 35 …”

Mimicking the Human Brain and More: New Grand Challenge Initiatives

“…In this regard, the use of layered transferred thin films or directly grown one-or two-dimensional semiconductors is an attractive approach. 11 However, with 3D device integration, power consumption and heat dissipation need to be carefully addressed. Of particular importance is the development of a new electronic switch that can operate at significantly lower voltages (and thus power) than conventional metal oxide semiconductor field-effect transistors (MOSFETs).…”

The 2008 Kavli Prize in Nanoscience: Carbon Nanotubes

“…44 Since then, Lieber and others have demonstrated the syntheses of a wide range of NW materials, including heterostructures (Figure 4) [45][46][47] with advanced and well-defined functionalities and properties while controllably assembling them into hierarchical structures ( Figure 5) and configuring them for a wide range of applications. [48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66] Properties and Applications. While the material properties of carbon nanotubes are primarily governed by their chirality (and thus, their diameter), for NWs, the properties are tuned by both the diameter and the elemental composition, which adds another handle in controlling functionality.…”

“…Furthermore, the low processing temperatures for crystalline NWs enable multilayer stacking of high-performance electronic and sensor elements for multifunctional, 3-D integration. 54,55 Interestingly, NWs can be assembled as highly ordered arrays by contact printing on unconventional substrates, such as plastic, glass, or paper for high-performance, "printable" macroelectronics ( Figure 5). 56,57 Semiconductor NWs have also been utilized for harvesting solar, mechanical, and thermal energies.…”