News and New Products

Organic Polymer Builds Tunnel Diode

By Harry Yeates -- Electronics Weekly, 11/22/2005

Researchers in the United States have used an organic polymer to build a tunnel diode that operates at room temperature at a voltage of 4V. They said it could be used to enable the simple, low-cost manufacture of memory products and smart cards.

Paul Berger, a Professor at Ohio State University, used the MEH-PPV polymer, which researchers in his group have previously shown to exhibit negative differential resistance. However, rather than trying to manipulate individual molecules to create a functional device, Berger painted a thick layer of the plastic onto an indium tin oxide (ITO) anode, with a TiO2 tunneling layer sandwiched in between.

This approach, of linking polymer to titanium oxide, has been tried before, but this time Berger initially deposited a layer of pure titanium on a chip, then oxidized it later, forming a 2-8nm layer.

“The titanium dioxide is the key [to the NDR],” Berger said. “In our experiments, when we replace it with anything else, the phenomenon goes away.”

The researchers were able to combine two plastic tunnel diodes to form a simple logic gate.

Electronics Weekly is the London-based sister publication of Electronic News.