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January 10, 2017

Electrical engineers create transferrable 4H silicon-carbide nanomembrane

A new type of nanomembrane could enable flexible ultraviolet (UV) photodetectors for a wide range of applications such as water and air purification, UV missile guidance systems, and security systems.

Developed by Jack Ma, the Lynn H. Matthias Professor and Vilas Distinguished Achievement Professor of electrical and computer engineering at UW-Madison, and research assistant Munho Kim, the 4H-silicon carbide nanomembrane can be released from its source wafer and transferred on any arbitrary substrates. It also has very high light absorption capability at the UV range despite thinness on the order of 200 nanometers. “4H” refers to the most common and widely used lattice structure of silicon carbide.

The researchers published details of their advance in the January 2017 edition of the Journal of Material Chemistry C. Their work was featured as an inside front cover of the journal.

Unlike silicon and germanium, the 4H silicon carbide has a large bandgap energy, which enables its application for UV light absorption. Although silicon and germanium nanomembranes have proven their potential in various devices such as flexible transistors and photodetectors, the devices have limited applications in situations that require wide bandgap semiconductors.

While other researchers have fabricated various nanomembranes, Ma and Kim have are the first to create the transferrable 4H silicon-carbide nanomembrane. “We actually can transfer it on anywhere we want to,” says Ma.

One important aspect of the 4H silicon-carbide nanomembrane is that the material has a high thermal conductivity. “This property makes the photodetectors working at a high temperature where an efficient heat dissipation is very important,” says Ma. “Other wide bandgap materials have their own issues in stability at high temperatures.”

Ultimately, the flexible silicon-carbide nanomembranes open the door of possibility, says Ma. “This demonstration shows the developed material has great potential in high-performance and flexible UV photodetectors,” he says. “It shows the capabilities of high-absorption at the UV range and stable performance under bending conditions.”

This research was a collaboration with colleagues Weidong Zhou of the University of Texas-Arlington and Edo Waks of the University of Maryland-College Park, and their students.