Tunneling current modulation in atomically precise graphene nanoribbon heterojunctions

Abstract

Lateral heterojunctions of atomically precise graphene nanoribbons (GNRs) hold promise for applications in nanotechnology, yet their charge transport and most of the spectroscopic properties have not been investigated. Here, we synthesize a monolayer of multiple aligned heterojunctions consisting of quasi-metallic and wide-bandgap GNRs, and report characterization by scanning tunneling microscopy, angle-resolved photoemission, Raman spectroscopy, and charge transport. Comprehensive transport measurements as a function of bias and gate voltages, channel length, and temperature reveal that charge transport is dictated by tunneling through the potential barriers formed by wide-bandgap GNR segments. The current-voltage characteristics are in agreement with calculations of tunneling conductance through asymmetric barriers. We fabricate a GNR heterojunctions based sensor and demonstrate greatly improved sensitivity to adsorbates compared to graphene based sensors. This is achieved via modulation of the GNR heterojunction tunneling barriers by adsorbates.

Preparation, Bandgap Engineering, and Performance Control of Graphene Nanoribbons

“…Most recently, several essential advances have been made to offer original pathways to better regulate the performance of GNR-FETs. For example, monolayer heterojunctions of near-metallic GNR and large-gap GNR were inserted in FETs (Figure d,e) . The disparate sizes of the bandgap in segments of the GNR heterojunction were accessible through typical lateral fusion of 7-AGNR, forming rampantly aligned GNR heterojunction channels.…”

“…(f) ARPES images of GNR heterojunction channels before (left) and after (right) Li absorption. Reproduced with permission under a Creative Commons CC-BY License () from ref . Copyright 2021 Springer Nature Limited.…”

“…For example, monolayer heterojunctions of nearmetallic GNR and large-gap GNR were inserted in FETs (Figure 12d,e). 151 The disparate sizes of the bandgap in segments of the GNR heterojunction were accessible through typical lateral fusion of 7-AGNR, forming rampantly aligned GNR heterojunction channels. As discussed above, such fused GNR structures were terminated by 7-AGNRs as barriers in GQDs, 128 where the properties of heterojunctions were mainly harnessed by large-gap 7-AGNR segments.…”

Bulk-interface correspondence from quantum distance in flat band systems

“…If multiple dual-gates with interfaces aligned with each other can be fabricated, the same number of uniformly oriented 1D interface systems can be generated. The angle-resolved photoemission spectroscopy (ARPES) technique can also be used to observe the band structure of the interface states in such 1D systems [45][46][47]. Recently, various kagome materials hosting nearly flat bands such as Fe 3 Sn 2 , FeSn, and CoSn have been synthesized [48][49][50], and they are candidate systems to demonstrate the bulkinterface correspondence from the quantum distance experimentally.…”

First-Principles Calculations on Lateral Heterostructures of Armchair Graphene Antidot Nanoribbons for Band Alignment

“…32 However, the formation and electronic modulation of 2DLH composed of one single class of materials are still a challenge. 34 There are several ways to construct p−n junctions based on single materials now in experiments, like doping, 35,36 strain, 37,38 laser irradiation, 39 electron irradiation, 40 and ultraviolet ozone treatment. 41 Besides, a lot of theoretical work has also revealed that the devices made by 2DLH exhibit great advantages in the electronic properties.…”