CVD-Grown Monolayer Graphene-Based Geometric Diode for THz Rectennas.

Heng Wang,Garret Moddel,Pedro M F J Costa,John Stearns,Gaurav Jayaswal,Atif Shamim,Geetanjali Deokar

doi:10.3390/nano11081986

Heng Wang, Garret Moddel + Show 5 more

Open Access

https://doi.org/10.3390/nano11081986

Copy DOI

Abstract

For THz rectennas, ultra-fast diodes are required. While the metal–insulator–metal (MIM) diode has been investigated in recent years, it suffers from large resistance and capacitance, as well as a low cut-off frequency. Alternatively, a geometric diode can be used, which is more suitable due to its planar structure. However, there is only one report of a THz geometric diode based on a monolayer graphene. It is based on exfoliated graphene, and thus, it is not suitable for mass production. In this work, we demonstrate chemical vapor deposition (CVD)-grown monolayer graphene based geometric diodes, which are mass-producible. The diode’s performance has been studied experimentally by varying the neck widths from 250–50 nm, the latter being the smallest reported neck width for a graphene geometric diode. It was observed that by decreasing the neck widths, the diode parameters such as asymmetry, nonlinearity, zero-bias resistance, and responsivity increased within the range studied. For the 50 nm neck width diode, the asymmetry ratio was 1.40 for an applied voltage ranging from −2 V to 2 V, and the zero-bias responsivity was 0.0628 A/W. The performance of the diode was also verified through particle-in-cell Monte Carlo simulations, which showed that the simulated current-voltage characteristics were consistent with our experimental results.

Highlights

Researchers are devoting themselves to seek new energy sources which are safe, renewable, and environment-friendly [1,2,3]
(current-voltage) characteristics were measured for the geometric diode with different characteristics were measured for the geometric diode with different neck neck widths varying from 50 nm to 250 nm
Compared to the reported 75 nm neck width geometric diode based on exfoliated graphene, the proposed diode in this work had a neck width of 50 nm, which ensured completely ballistic transport, as the mean free path (MFP) of the graphene was 70 nm at zero VGS

Summary

Introduction

Researchers are devoting themselves to seek new energy sources which are safe, renewable, and environment-friendly [1,2,3]. The energy from waste heat is within the wavelength range of 2–11 μm, corresponding to frequencies of tens of Terahertz (THz) [4] Since this IR energy can be considered as very high-frequency electromagnetic waves, they can be captured by a receive antenna and rectified by a diode into direct current (DC). This combination of a receive antenna integrated with a rectifying diode is typically known as a rectenna [5], which is quite common in the microwave frequency range but very challenging to realize in the THz domain This approach can provide sustainable energy for 24 h a day without adding any pollution to the environment.

Objectives

Methods

Results

Conclusion