Experimental evidence of negative quantum capacitance in topological insulator for sub-60-mV/decade steep switching device

As a three-dimensional topologicalinsulator (TI), bismuth telluride (Bi2Te3) has two-dimensionalelectron gas on itssurface where negative quantumcapacitance (NQC) can exist at a specific biasing condition. In order to experimentally confirm NQC in a TI, a metal –insulator–semiconductor (MIS)capacitor (i.e., metal –Bi2Te3–SiO2–silicon) is fabricated. The capacitance–voltage measurement of theMIS capacitor at 300  K shows that as the depletioncapacitance insilicon decreases, the totalcapacitance of theMIS capacitor, which consists of twocapacitors connected in series (i.e.,insulatorcapacitor and depletioncapacitor), increases in the depletion region at a frequency of 50  kHz. The amplifiedcapacitance indicates the existence of NQC on thesurface of the TI, and it originates from the strongly correlated electron system. The NQC of the TI opens avenues for sub-60-mV/decade steep switchingsilicon devices.

Source: Applied Physics Letters - November 16, 2016 Category: Physics Authors: H. Choi, H. Lee, J. Park, H.-Y. Yu, T. G. Kim and C. Shin Source Type: research