Hot carrier relaxation in three dimensional gapped Dirac semi-metals

Abstract

We calculate the relaxation rate of hot carriers in a Cd3As2 semi-metal with a finite gap. The quantization of the transverse momentum gives rise to a minimum gap at the Dirac point. Additional chemical doping further increases the gap. A finite gap relaxes the selection rule and gives rise to a nonvanishing internode coupling via phonon scattering. The gap also enhances the intra-node scattering. It is shown that the relaxation rate is proportional to the square of the gap. By considering the decay of the electron distribution function, we find that the relaxation rate increases with the square of the gap and the electron temperature.

Hot electron cooling in Dirac semimetal Cd3As2 due to polar optical phonons

“…The hot electron energy relaxation by emission of acoustic and optical phonons has been extensively investigated theor etically and experimentally in conventional 3D electron gas (3DEG) in bulk semiconductors [25][26][27][28][29][30][31], 2D electron gas (2DEG) in semiconductor heterostructures [31,32], mono layer graphene [33] and bilayer graphene [34]. Recently, hot electron cooling is theoretically studied in monolayer MoS 2 [35] and quasi2DEG in gapped Cd 3 As 2 film [36]. There exist theoretical studies of hot 3D Dirac fermion cooling power due to electronacoustic phonon interaction P ac in Cd 3 As 2 [37,38] 4 .…”

Relativistic suppression of Auger recombination in Weyl semimetals

“…Visualization of AR in WSM: temporal dynamics.-Once the interband population inversion is created in WSM, its relaxation after relatively fast intraband equilibration (due to electron-electron scattering) is governed by the interband processes. Assuming that AR lifetime in WSM is shorter than the phonon-limited lifetime 39 , we consider the temporal dynamics with AR channel only,…”

Broadband photocarrier dynamics and nonlinear absorption of PLD-grown WTe2 semimetal films

“…For example, it has been demonstrated that cadmium arsenide (Cd 3 As 2 ), a three-dimensional Dirac semimetal, exhibits a broadly tunable photocarrier lifetime in the mid-wave infrared (3-6 lm), as driven by symmetry-breaking induced gap-opening. [4][5][6] Optoelectronic devices such as fast photodetectors with promising figures-of-merit were also realized using cadmium arsenide. 7,8 Transition metal dichalcogenide WTe 2 , also deemed a type-II Weyl semimetal candidate, exhibits extraordinary properties such as large unsaturated magnetoresistance (MR) and exotic superconducting behaviour under high pressure.…”