New microchip material is 10 times stronger than Kevlar

NOV 04, 2023

Researchers at Delft University of Technology have created a novel material that has a yield strength ten times higher than Kevlar, rivaling the strength of other super strong alternatives such as graphene and diamonds.

High-strength synthetic fibers like Kevlar are renowned for their remarkable resilience to abrasion and wear. They are most notably used in applications that are reinforcing and strengthening, particularly in body armor, helmets, and other protective gear.

Going beyond protective gear

The new material is called amorphous silicon carbide (a-SiC) and could have a host of applications that go beyond protective gear to enabling highly sensitive microchips.

“To better understand the crucial characteristic of "amorphous", think of most materials as being made up of atoms arranged in a regular pattern, like an intricately built Lego tower,” explained assistant professor Richard Norte who led the new work.

“These are termed as "crystalline" materials, like for example, a diamond. It has carbon atoms perfectly aligned, contributing to its famed hardness.”

However, amorphous materials are devoid of a consistent arrangement. This randomization does not lead to fragility as one might assume. Amorphous silicon carbide, in fact, provides proof that strength can arise from unpredictability as the material boasts a tensile strength of 10 GigaPascal (GPa).

“To grasp what this means, imagine trying to stretch a piece of duct tape until it breaks. Now if you’d want to simulate the tensile stress equivalent to 10 GPa, you'd need to hang about ten medium-sized cars end-to-end off that strip before it breaks,” said Norte.

In addition to its remarkable strength, this material exhibits mechanical qualities that are essential for vibration isolation on a microchip. Thus, amorphous silicon carbide is especially well suited for creating extremely sensitive microchip sensors.

A microchip-based method for material testing

To study this unique application potential, the researchers employed a microchip-based method for material testing, which guarantees previously unheard-of precision. They were able to create high tensile forces by growing the amorphous silicon carbide films on a silicon substrate and suspending them. This was made possible by the nanostrings' shape.

They then proceeded to carefully monitor the point of breakdown of the materials by creating numerous of these structures with progressively higher tensile stresses. Nanostrings were employed as the basis upon which more complex suspended structures can be built because exhibiting high yield strength in the components is equivalent to displaying strength in their most elemental form.

The researchers reported that the new material is highly scalable especially compared to other alternatives such as graphene and diamonds which are costly and inefficient to produce. As such, amorphous silicon carbide is extremely promising for applications ranging from cutting-edge space exploration tools and DNA sequencing technologies to highly sensitive microchip sensors and sophisticated solar cells.

“With amorphous silicon carbide's emergence, we're poised at the threshold of microchip research brimming with technological possibilities,” said Norte.

The study is published in the journal Advanced Materials.

Study abstract:

For decades, mechanical resonators with high sensitivity have been realized using thin-film materials under high tensile loads. Although there have been remarkable strides in achieving low-dissipation mechanical sensors by utilizing high tensile stress, the performance of even the best strategy is limited by the tensile fracture strength of the resonator materials. In this study, a wafer-scale amorphous thin film is uncovered, which has the highest ultimate tensile strength ever measured for a nanostructured amorphous material. This silicon carbide (SiC) material exhibits an ultimate tensile strength of over 10 GPa, reaching the regime reserved for strong crystalline materials and approaching levels experimentally shown in graphene nanoribbons. Amorphous SiC strings with high aspect ratios are fabricated, with mechanical modes exceeding quality factors 108 at room temperature, the highest value achieved among SiC resonators. These performances are demonstrated faithfully after characterizing the mechanical properties of the thin film using the resonance behaviors of free-standing resonators. This robust thin-film material has significant potential for applications in nanomechanical sensors, solar cells, biological applications, space exploration and other areas requiring strength and stability in dynamic environments. The findings of this study open up new possibilities for the use of amorphous thin-film materials in high-performance applications.

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