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Engineering researchers discover innovative hybrid ceramic transistor

By Kayla J. Kayden
University News Service
October 8, 2014

A research group at Texas State University Ingram School of Engineering has discovered a new type of hybrid transistor that can potentially protect circuits from power surges.

The research on "varistor embedded ceramic transistors" was published in Ceramic Tech Today, a publication of the American Ceramic Society.

The research group, headed by engineering professor Kumar Pandey, was working on varistors and changing the current response by different methods.  It was only after Pandey evaluated the large amount of data collected by undergraduate students working under him that he realized transistors appeared to be embedded in the varistors.

The discovery came as a surprise to Pandey, because this type of hybrid had not been seen or reported.  He consulted with William Stapleton, an assistant professor in the Ingram School of Engineering, who confirmed his interpretation. The team continued with many more experiments using different ceramic materials each time, only to obtain the same results, confirming the discovery.

Pandey, Stapleton and three undergraduate students of the electrical engineering program were involved in the discovery.

A varistor, made of ceramic oxides, is a device that is present in electric and electronic circuits.  When a current or voltage exceeds its maximum, a varistor prevents the circuit from being destroyed by preventing the excess electricity from entering.  A transistor, made of highly purified silicon in the form of bulk single crystals or films, acts like an electronic switch and amplifies the current while it acts like a filter.

The hybrid devices are built on ceramic substrates, which are simple to process and can be produced on a large scale inexpensively, whereas materials for a transistor are time consuming, costly and a highly sophisticated technology.  The devices can be used as a varistor or transistor simultaneously, and allows for the use of less electrical power by amplifying. 

Pandey said the potential of the discovery is “certainly great,” but it will take time.

“It will take some time, it is the simplicity of the device structure and its potential to impact electronics and microelectronics in big ways that might draw the attention to this trend-setting discovery of scientists and engineers,” Pandey said. 

Pandey said the discovery of the hybrid devices has been personally rewarding in the ways of making contributions to science and Texas State.

“Personal satisfaction and a sense of achieving something big and making a long-lasting contribution to science and engineering, while contributing to the external visibility of Texas State and enhancing its stature among peers,” Pandey said.

For more information, please contact R. Kumar Pandey at