Near-field thermal rectification devices using phase change periodic nanostructure.

Alok Ghanekar,Sinong Zhang,Matthew Ricci,Otto Gregory,Yanpei Tian,Yi Zheng

doi:10.1364/oe.26.00a209

Abstract

We theoretically analyze two near-field thermal rectification devices: a radiative thermal diode and a thermal transistor that utilize a phase change material to achieve dynamic control over heat flow by exploiting metal-insulator transition of VO2 near 341 K. The thermal analogue of electronic diode allows high heat flow in one direction while it restricts the heat flow when the polarity of temperature gradient is reversed. We show that with the introduction of 1-D rectangular grating, thermal rectification is dramatically enhanced in the near-field due to reduced tunneling of surface waves across the interfaces for negative polarity. The radiative thermal transistor also works around phase transition temperature of VO2 and controls heat flow. We demonstrate a transistor-like behavior wherein heat flow across the source and the drain can be greatly varied by making a small change in gate temperature.

Highlights

Thermal analogues of electronic rectification devices such as thermal diodes [1], thermal transistors [2] and memory elements [3] have been studied during past decade
We have theoretically demonstrated that an enhanced thermal rectification can be achieved in a thermal diode and a thermal transistor by using 1-D grating of phase change material VO2
For the near-field thermal diode considered in the study, we predict a reasonably high value of rectification ratio (∼ 14) that can be obtained at a gap of 100 nm

Summary

Introduction

Thermal analogues of electronic rectification devices such as thermal diodes [1], thermal transistors [2] and memory elements [3] have been studied during past decade. Following Ben-Abdallah and Biehs’s work on a VO2 based simple far-field radiative thermal diode, numerous studies on thermal rectification [16,17,18,19], thermal transistors [20], negative differential conductance [21] have been published. Present study focuses on rectification in a near-field thermal diode and a near-field thermal transistor that employ VO2 as phase-transition material. In the present study, grating-enhanced near-field thermal diode introduced in [28] is revisited and the concept is extended to near-field thermal transistor. When T1 > T2 (referred to as forward bias), VO2 layer is in metallic phase; when T1 < T2 (reverse bias), VO2 layer is in insulator phase with its optical axis aligned along the distance between them This provides a better insight into transistor-like behavior of proposed device

Theoretical fundamentals

Results

Conclusion