Achieving Type I, II, and III Heterojunctions Using Functionalized MXene

Abstract

In the present work, type I, II, and III heterostructures are constructed with the same base material using three representative functionalized monolayer scandium carbides (Sc2CF2, Sc2C(OH)2, and Sc2CO2) by first-principles calculations based on density functional theory. In contrast to general bilayer heterosystems composed of two-dimensional semiconductors, type I and III heterojunctions are obtained in one Sc2CF2/Sc2CO2 system and the remains of the functionalized Sc2C heterostructures, respectively. It is noteworthy that the same monolayer Sc2CF2 and Sc2CO2 constituents lead to dissimilar heterostructure types in the two Sc2CF2/Sc2CO2 systems by modifying the stacking interface. In addition, in the two Sc2CF2/Sc2CO2 systems, remarkable changes in the heterojunction type are induced by a strain, and two distinct type-II heterostructures are generated where one layer with the conduction band minimum state and the other layer including the valence band maximum level are different. The present work suggests an attractive direction to obtain all heterostructure types with the same base material for novel nanodevices in various fields such as photonics, electronics, and optoelectronics using only the two monolayer components Sc2CF2 and Sc2CO2.

Prediction of T‐ and H‐Phase Two‐Dimensional Transition‐Metal Carbides/Nitrides and Their Semiconducting–Metallic Phase Transition

“…Namely, semiconducting–metallic phase transitions will be achieved when T‐phase Ti 2 CO 2 is transformed into H‐phase. Similarly, as shown in Figure S2, T‐phase Sc 2 CO 2 and Sc 2 CO 2 H 2 have band gaps of 2.08 and 0.49 eV, respectively, which agrees with Lee's results with band gaps of 1.86 and 0.34 eV . However, their corresponding H phases show no band gap, which also could be applied to semiconducting‐metallic phase transition.…”

Electronic properties and applications of MXenes: a theoretical review

“…The basic idea behind the stacking of different 2D layers is the band gap engineering and combining the electronic properties of different 2D layers together into a single 3D crystalline composite with substantially tailored electronic properties. For example, the electronic structures of Graphene/Hf 2 C(OH) 2 [42], MoS 2 /Ti 2 C, MoS 2 /Ti 2 CT 2 (T = F and OH) [73], silicine/Sc 2 CF 2 [74], Sc 2 CF 2 /Sc 2 CO 2 [75], and various transition metal dichalcogenides/M 2 CO 2 (M=Sc, Ti, Zr, and HF) [179,180] heterostructures have been studied based on first-principles calculations.…”

“…Some of MXenes are predicted to be topological insulators with large band gaps involving only d orbitals [67][68][69][70][71]. MXenes are also expected to be used as ultralow work function materials [72] and Schottky barrier junctions [73][74][75][76].…”

Recent advances in MXene: Preparation, properties, and applications

“…In fields other than electrochemistry, MXenes' unique structures and properties provide the material class with many other potential applications, including adsorbents [16,65], hydrogen storage media [66,67], catalyst supporters [21,68,69], additives [70,71], and many others [72][73][74][75]. However, many of these applications are still hypothetical or at the fundamental stage.…”