Ultrafast Broadband Photodetectors Based on Three-Dimensional Dirac Semimetal Cd₃As₂

Abstract

Abstract:The efforts to pursue photo detection with extreme performance in terms of ultrafast response time, broad detection wavelength range, and high sensitivity have never been exhausted as driven by its wide range of optoelectronic and photonic applications such as optical communications, interconnects, imaging and remote sensing 1 . 2D Dirac semimetal graphene has shown excellent potential toward high performance photodetector with high operation speed, broadband response and efficient carrier multiplications benefiting from its linear dispersion band structure with high carrier mobility and zero bandgap [2][3][4] . As the three dimensional analogues of graphene, Dirac semimetal Cd3As2 processes all advantages of graphene as a photosensitive material but potentially has stronger interaction with light as bulk material and thus enhanced responsivity 5,6 , which promises great potential in improving the performance of photodetector in various aspects . In this work, we report the realization of an ultrafast broadband photodetector based on Cd3As2. The prototype metal-Cd3As2-metal photodetector exhibits a responsivity of 5.9 mA/W with response time of about 6.9 ps without any special device optimization. Broadband responses from 0.8 eV to 2.34 eV are measured with potential detection range extendable to far infrared and terahertz. Systematical studies indicate that the photo-thermoelectric effect plays important roles in photocurrent generation, similar to that in graphene. Our results suggest this emerging class of exotic quantum materials can be harnessed for photo detection with high sensitivity and high speed (~145 GHz) in challenging middle/far-infrared and THz range.Three dimensional Dirac semimetal Cd3As2 7,8 is a stable compound with ultrahigh carrier mobility up to 9×10 6 cm 2 V -1 S -1 (refs. 9-11), as a result of supressed backscattering of high Fermi velocity 3D Dirac fermions 9 . The high mobility of Cd3As2 surpasses suspended graphene and any bulk semiconductors, promising for new electronics and optoelectronics with supereme performance 5,6 . Comparing to their two dimensional counterpart graphene 5,6,12,13 and surface state of topological insulator 14 , 3D Dirac semimetals are more robust against enviromental defects or excess conducting bulk electrons 11 . On the other hand, 3D Dirac semimetals possess all advantages of 2D Dirac semimetals as photosensitive materials, which is inherent from the gapless linear dispersion of massless Dirac Fermions: extermely high mobility 9 and ultrafast transient time 15 for high speed response approaching terahertz operation speed 4,16 ; gapless bandstructure for chanlleging low energy photon detection 17 down to THz frequency [18][19][20] and efficient carrier multiplications to enhance the internal quantum efficiency 21,22 . Consequently, the emergency of stable 3D Dirac semimetal Cd3As2 provides outstanding opportunity as new class of material platform for optoelectronics.Experimental studies on Cd3As2 so far mainly focus on the tranport and angle resolved...

Terahertz probe of photoexcited carrier dynamics in the Dirac semimetal Cd3As2

“…The interplay and related dynamical processes between carriers, phonons and other quasiparticles have strong influence on the devices performance especially when the device is running at high speed and high field limit. So far, the ultrafast spectroscopy investigations of the (quasi)particle dynamics of Cd3As2 and other 3D Dirac semimetals are still limited to visible and near/midinfrared region and the theoretical studies related to these aspects have been limited to hot carriers relaxation [22][23][24][25][26][27], photoelectric response [28], phonon dynamics and electron-phonon interactions (especially, the acoustic phonon which is dominant at very low temperature in scale of Kelvin where the electronic temperature is lower than the lowest optical phonon branch) [29][30][31][32]. The intraband carrier relaxation dynamics, intraband optical response and intraband optical conductivity of 3D Dirac semimetallic Cd3As2 remains unexplored experimentally, which are crucial for electron transport and optoelectronic operations considering the fact that semimetals are easily doped.…”

Similar ultrafast dynamics of several dissimilar Dirac and Weyl semimetals

“…It reveals properties of the hot electrons important in high-field devices. More directly, it can guide optoelectronic applications: recently several devices have been reported that rely on the ultrafast properties of Cd 3 As 2 , the archetypal three-dimensional Dirac semimetal, to make fast photodetectors 23,24 and optical switches. 25 The monopnictide Weyl materials TaAs, TaP, and NbAs also show technological promise due to their sizable, anisotropic nonlinear-optical response.…”

“…34 The materials' optoelectronic properties thus persist from the visible through the mid-infrared. 23,25 In this work we investigate the ultrafast dynamics of four Dirac and Weyl materials: TaAs and NbP; 5,12 ZrSiS; 48 and Sr 1−y Mn 1−z Sb 2 . 49 As shown in Fig.…”

Dynamically Induced Excitonic Instability in Pumped Dirac Materials

“…Due to the great potential of DMs for high‐performance optoelectronic devices, non‐equilibrium dynamics of DMs has emerged as an important research topic. Many studies have focused on the interplay between light and Dirac states and, in particular, on optical generation and control of spin‐polarized currents on TI surfaces .…”