Thickness‐Dependent Carrier Transport Characteristics of a New 2D Elemental Semiconductor: Black Arsenic

Abstract

2D elemental layered crystals, such as graphene and black phosphorus (B-P), have received tremendous attentions due to their rich physical and chemical properties. In the applications of nanoelectronic devices, graphene shows super high electronic mobility, but it lacks bandgap which impedes development in logical devices. As an alternative, B-P shows high mobility of up to about 1000 cm 2 V −1 s −1 . However, B-P is very unstable and degrades rapidly in ambient conditions. Orthorhombic arsenic (black arsenic; b-As) is the "cousin" of B-P; theoretical prediction shows that b-As also has excellent physical and chemical properties, but there is almost no experimental report on b-As. Herein, it is reported on the unique transport characteristics and stability of monolayer and few-layer b-As crystals which are exfoliated from the natural mineral. The properties of field-effect transistors (FETs) strongly depend on the thickness of crystals. In the monolayer limit, the performance shows relatively high carrier mobilities and large on/off ratios. Moreover, the b-As crystals exhibit a relatively good ambient stability. The few-layer arsenic based FET still function after exposure to air for about one month. Therefore, b-As is expected to be a promising 2D material candidate in nanoelectronic devices.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.201802581.properties. [9][10][11] It is considered to be a more promising material than graphene in opto/ nanoelectronic devices. [1,5,6,8,9] However, the deterioration of B-P under atmospheric conditions definitely hinders its applications in practical devices. [12,13] To improve its performance, many attempts have been made. Studies have found that alloying of B-P is a good choice, such as the black arsenic-phosphorus alloy shows tunable bandgap, excellent optical properties, and good ambient stability. [14,15] Another way is to find the new alternative materials.B-As (named arsenene), as a cousin of B-P, has the similar structure configuration with B-P, which is expected to have excellent physical and chemical properties. [16][17][18] Just like most TMDCs and B-P, theoretical studies have verified that the band structures of b-As also have layer dependence. [16] Bulk layered b-As is a direct semiconductor with the bandgap of about 0.3 eV, whereas the monolayer b-As is an indirect bandgap semiconductor with the gap value of about 1-1.5 eV. [16][17][18][19][20] This characteristic leads it to a possibility for applications in optoelectronic and logical devices. Moreover, few-layer b-As is predicted to have high carrier mobility (several thousand square centimeters per volt-second). [20,21] These excellent physical properties make it a good candidate for applications in electronic devices. So far, the experimental synthesis of black arsenic crystals still faces great challenges. [22,23] A recent paper reported that black arsenic is metastable and often stabilized by impurities; and it is very difficult to synt...

Thermal Transport in 2D Semiconductors—Considerations for Device Applications

“…As a cousin of black phosphorene, black arsenic (b‐As) has just been fabricated and shows interesting anisotropic transport behaviors in electrical and thermal properties . Its puckered atomic structure, shown in Figure d, is similar to that of black phosphorene.…”

Recent advances in low‐dimensional semiconductor nanomaterials and their applications in high‐performance photodetectors

“…Both theoretical and experimental characterization have demonstrated that B‐As is a layered material similar to B‐P, and the band structure is related to the number of layers. The bulk B‐As bandgap is about 0.3 eV, which is a direct bandgap; the single layer is about 1.5 eV, which is an indirect bandgap . Most importantly, B‐As has a stronger anisotropy .…”

“…Previous work has shown that pure B‐As is metastable, so it can be only stabilized by impurities (such as B‐AsP), which is why the content of As in B‐AsP can only reach 0.83 . It is difficult for the laboratory to synthesize B‐As, but there are natural minerals of B‐As in nature . Both theoretical and experimental characterization have demonstrated that B‐As is a layered material similar to B‐P, and the band structure is related to the number of layers.…”

“…C, Output characteristics of the same device at different gate voltages. Reproduced with permission . Copyright 2018, Wiley‐VCH.…”

“…In the study of low‐dimensional materials, the FETs are commonly used to study the carrier transport characteristics in electric fields. Here, the elemental 2D material B‐As is taken as an example . A thin‐layer of material is prepared by mechanical exfoliation; then the electrodes are prepared by a series of means such as standard electron beam lithography and formed through e‐beam evaporation and lift‐off process.…”