PtTe₂‐Based Type‐II Dirac Semimetal and Its van der Waals Heterostructure for Sensitive Room Temperature Terahertz Photodetection

Abstract

The conversion of light into electrical signals is at the heart of a plenty of technologies related with everyday life, such as optical communication, remote sensing, security, and many other fields. [1] The continuous extension of application areas requires progressive development of portable photodetectors with high performance in terms of speed, efficiency, or active wavelength range. [2] Recent years have witnessed the burgeoning interests in exploiting the optical and electronic properties of layered materials due to their weak interlayer van der Waals (vdW) interaction and dangling-bond-free surfaces for high-quality integration. [3] Compared with traditional materials, such as GaAs, Si, and Ge, the quantum behavior of electrons in 2D materials can be distinctive different from their bulk parental materials, which shows strong layer-dependence and composed properties in vdW heterostructure, and revolutionizes the way of manipulation, conversion of nonequilibrium carriers under strong light-matter interaction. Over the past few years, 2D materials such like graphene, [4] black phosphorus, [5] h-BN, [6] and MoS 2 [7] and their heterostructures have been widely implemented in a variety of photonic and electronic systems, showing appealing novel properties for single photon source, exciton/plasmon/phonon polaritons, artificial diode for transparent electronic and photovoltaic devices, and open up novel feasibility for realizing optoelectronic devices across a very wide range of electromagnetic spectrum. Up to now, significant efforts have been devoted to develop photodetectors capable of working toward longer wavelength in the 2D quantum materials family, based on a number of distinct characteristics of graphene and related materials. [8] However, the detecting wavelength of these detectors is mainly limited within visible to short-wavelength infrared due to their unmatched dark current, carrier mobility, and bandgap properties. For example, the detectable wavelength of WS 2 is shorter than 647 nm [9] and the black phosphorus can work at wavelength shorter than 7.7 µm. [10,11] For longer wavelength photodetection, liquid helium cooling or even dilute cooling is required in order to inhibit noise from intrinsically large dark current or the thermally induced transition among closely lying energylevels. [12] In compared with other electromagnetic radiation Recent years have witnessed rapid progresses made in the photoelectric performance of two-dimensional materials represented by graphene, black phosphorus, and transition metal dichalcogenides. Despite significant efforts, a photodetection technique capable for longer wavelength, higher working temperature as well as fast responsivity, is still facing huge challenges due to a lack of best among bandgap, dark current, and absorption ability. Exploring topological materials with nontrivial band transport leads to peculiar properties of quantized phenomena such as chiral anomaly, and magnetic-optical effect, which enables a novel feasibility for an advanced optoele...

Van der Waals Epitaxial Growth of Mosaic‐Like 2D Platinum Ditelluride Layers for Room‐Temperature Mid‐Infrared Photodetection up to 10.6 µm

“…Recently, PtTe 2 , a newly discovered 2D noble metal dichalcogenide candidate, has come under the spotlight due to its fascinating transition from semiconductor (monolayer) to type‐II Dirac semimetal (bulk), excellent air stability, and versatile optoelectronic applications, [ 17 ] especially in MIR sensing. To date, the most studies are primarily dependent on chemical vapor transport (CVT)‐synthesized bulk materials, [ 17 ] chemical vapor deposition (CVD)‐grown nanosheets, [ 18 ] mechanically exfoliated flakes, [ 19 ] and micron‐sized single crystals prepared by a solid‐liquid‐solid (SLS) method. [ 20 ] However, PtTe 2 obtained by these synthetic approaches stuck with either uncontrollable layer numbers or small sizes, hindering their large‐area integrated device application.…”

“…It is believed that such structure can greatly facilitate the carrier separation and reduce carrier recombination after generation of electron–hole pairs under light illumination. [ 19,45 ] This may also contribute to the enhanced photocurrent. Figure 5d compares the PtTe 2 /Si photodetector with the photodetectors based on 2D materials in prior reports and the commercial products.…”

“…[17,18] Unlike graphene-like type-I semimetal, PtTe 2 has been discovered as a type-II topological semimetal with a strongly tilted Dirac cone (Figure 1a), which demonstrates unique chiral anomaly-related transport and anisotropic magneto-transport properties, rendering great potential for future polarization-sensitive photodetection applications. [17][18][19] As shown in Figure 1b,c, within a single layer, one Pt atom strongly connects to six Te atoms in a repetitive hexagonal unit cell, and the single stacking layers of PtTe 2 along the zaxis are held together by weak vdW interaction. In this work, a scalable and facile tellurium-vapor transformation approach has been proposed for the vdW epitaxial growth of wafer-scale 2D PtTe 2 layer using pre-deposited Pt film as a precursor ( Figure S1, Supporting Information).…”

Imaging and identification of point defects in PtTe2

“…It has been shown to be a type-II Dirac semimetal 18 with high conductivity 19 , suggesting it may be suitable for applications in spintronics and quantum computing [20][21][22] . Recently, the potential use of PtTe 2 in a variety of different applications, such as electrocatalysis 11,23,24 , ultrafast photonics 25 , and terahertz photodetection 26 has been reported.…”

Progress in Epitaxial Thin‐Film Na3Bi as a Topological Electronic Material

“…[ 173,174 ] Based on the same principles, photodetecting devices have been realized with the topological insulator Bi 2 Te 3 [ 175 ] and the type‐II Dirac semimetal PtTe 2 . [ 176 ] Presently photodetection from a Na 3 Bi device remains unreported, but we anticipate that the linearity of the electron dispersion, high mobility of the carriers, and demonstrated growth of large‐area crystals stabilized with optically transparent capping‐layers, make Na 3 Bi a suitable platform for photodetection applications.…”