Measurement of Field-Assisted Thermal Electron Tunneling between Single Crystal Silicon Cleavage Plane Nanogap

Abstract

Thermoelectric power generation using nanogaps is attracting attention as a highly efficient direct power generation method from heat that can be operated at room temperature, but it is still a theoretical prediction and has hardly been experimentally verified. In this study, we created a nanogap by cleavage fracture of a single-crystal silicon beam fabricated on a micro electro mechanical system (MEMS) device in order to clarify the temperature characteristics of field electron tunneling between the nanogaps. This MEMS device can change the gap distance by electrostatic actuators after the fabrication of the gap, apply bias voltage between the gap, and Joule heating at one end of the gap. We measured the tunneling current across the gap as a function of bias voltage and temperature. As a result, the tunneling current increased proportionally to the temperature difference at the gap, which is consistent with the theoretical calculation of the field electron tunneling between the gaps considering the thermal excitation of electrons. This result strongly suggests that the measured current is due to the electron tunneling through the nanogap, indicating the effectiveness of the proposed method.