Tech Startup Unveils Printed-Silicon Transistor

By Mary Catherine O'Connor

Nov. 14, 2007—In the world of electronics, RFID tags are relatively simple devices, consisting of a low-memory integrated circuit (IC) and an antenna. And yet, to date, the RFID industry has had to rely on the same basic, time- and resource-consuming silicon fabrication processes for making the integrated circuits as other industries that produce more advanced electronics.

For that reason, considerable research has gone into developing ICs without silicon, instead using organic, polymeric semiconductors than can be deposited through printing processes. OrganicID, PolyIC and other firms have had some success in building out tag prototypes, but such tags tend to perform poorly compared to silicon-based tags.

Amir Mashkoori

While silicon is a better conductor than organic materials, printing with silicon-based inks has been considered impossible. Now, however, a venture-backed firm in Silicon Valley called Kovio claims it has found a way to do just that, and has unveiled a thin-film transistor (TFT) printed with a silicon ink using an ink-jet printing process. The transistor is a building block for a complete IC, which will contain multiple TFTs used for different functions on the chip. Kovio's CEO and chairman, Amir Mashkoori, says that by the end of next year, his company expects to have a fully functional printed-silicon integrated circuit that will be used to make high-frequency (HF) RFID tags.

According to Mashkoori, although Kovio is not the first company to be able to print thin-film transistors with silicon, its offering has the highest charge mobility of any silicon-based printed TFT. The high charge mobility of the Kovio TFT, Mashkoori explains, enables it to support the transmission of ultra-high frequency (UHF) RF signals, which other TFTs and transistors printed with organic materials can not do (see Printed RFID Tags Still Several Years Away).