Voltage biased Varistor-Transistor Hybrid Devices: Properties and Applications

The paper describes the properties and potential applications of a novel hybrid varistor device originating from biased voltage induced modified nonlinear current-voltage (I-V) characteristics. Single crystal of an oxide semiconductor in the family of iron-titanates with the chemical formula of Fe₂TiO₅ (pseudobrookite) has been used as substrate for the varistor. The modifications of the varistor characteristics are achieved by superimposition of a bias voltage in the current path of the varistor. These altered I-V characteristics, when analyzed, reveal the existence of embedded transistors coexisting with the varistor. These transistors exhibit mutual conductance, signal amplification and electronic switching which are the defining signatures of a typical transistor. The tuned varistors also acquire the properties of signal amplification and mutual conductance which expand the range of applications for a varistor beyond its traditional use as circuit protector. Both tuned varistors and the embedded transistors have attributes which make them suitable for many applications in electronics including at high temperatures and for radiation dominated environments such as space