Planar and van der Waals heterostructures for vertical tunnelling single electron transistors

Gwangwoo Kim ,Matthew Holwill ,Artem Mishchenko ,Yong-Jin Kim ,Daria V Andreeva ,Davit Ghazaryan ,Young Jin Cho ,Hyun‐Jong Chung ,Jun Yin ,Sung Soo Kim ,Byeong‐Hyeok Sohn ,Seokmo Hong ,A K Geǐm ,A‐Rang Jang ,Seong In Yoon ,Abhishek Misra ,Hu Young Jeong ,Kostya S Novoselov ,Servet Ozdemir ,Jonghyuk Jeon ,Hyeon Suk Shin

doi:10.1038/s41467-018-08227-1

Abstract

Despite a rich choice of two-dimensional materials, which exists these days, heterostructures, both vertical (van der Waals) and in-plane, offer an unprecedented control over the properties and functionalities of the resulted structures. Thus, planar heterostructures allow p-n junctions between different two-dimensional semiconductors and graphene nanoribbons with well-defined edges; and vertical heterostructures resulted in the observation of superconductivity in purely carbon-based systems and realisation of vertical tunnelling transistors. Here we demonstrate simultaneous use of in-plane and van der Waals heterostructures to build vertical single electron tunnelling transistors. We grow graphene quantum dots inside the matrix of hexagonal boron nitride, which allows a dramatic reduction of the number of localised states along the perimeter of the quantum dots. The use of hexagonal boron nitride tunnel barriers as contacts to the graphene quantum dots make our transistors reproducible and not dependent on the localised states, opening even larger flexibility when designing future devices.

Highlights

The high-quality hexagonal boron nitride (hBN) monolayer was first grown on Pt foils via chemical vapour deposition (CVD), using ammonia borane as a precursor[17]
The hBN on top of Pt NPs was selectively converted to graphene, with the formation of uniform Graphene quantum dots (GQDs) arrays embedded in the hBN film (Supplementary Figure 2)
The as-prepared GQD-hBN in-plane heterostructure was placed in aqua regia solution to remove Pt NPs (Fig. 2g–i), and transferred onto arbitrary substrates for further characterisation and processing

Summary

Introduction

Results Formation of GQDs. In order to fabricate the in-plane graphene/ hBN heterostructures, we used a conversion reaction on a patterned Pt-SiO2 substrate described in ref. The hBN on top of Pt NPs was selectively converted to graphene, with the formation of uniform GQD arrays embedded in the hBN film (Supplementary Figure 2).

Results

Conclusion