Charge Mobility and Recombination Mechanisms in Tellurium van der Waals Solid

Abstract

Trigonal tellurium is a small band gap elemental semiconductor consisting of van der Waals bound one-dimensional helical chains of tellurium atoms. We study the temperature dependence of the charge carrier mobility and recombination pathways in bulk tellurium. Electrons and holes are generated by irradiation of the sample with 3 MeV electrons and detected by time-resolved microwave conductivity measurements. A theoretical model is used to explain the experimental observations for different charge densities and temperatures. Our analysis reveals a high room temperature mobility of 190 ± 20 cm2 V–1 s–1. The mobility is thermally deactivated, suggesting a band-like transport mechanism. According to our analysis, the charges predominantly recombine via radiative recombination with a radiative yield close to 98%, even at room temperature. The remaining charges recombine by either trap-assisted (Shockley–Read–Hall) recombination or undergo trapping to deep traps. The high mobility, near-unity radiative yield, and possibility of large-scale production of atomic wires by liquid exfoliation make Te of high potential for next-generation nanoelectronic and optoelectronic applications, including far-infrared detectors and lasers.

Infrared ultrafast spectroscopy of solution-grown thin film tellurium

“…The radiative recombination coefficient was obtained as 1.9 ∓ 0.1 × 10 −9 cm 3 /s. Our value is lower than the 1.1 × 10 −8 cm 3 /s obtained by Bhaskar et al [44] but higher than other traditional direct-band-gap semiconductors such as GaAs, which has a value of ∼7 × 10 −10 cm 3 /s at room temperature. The surface recombination velocity is found as V s = 2×10 6 t cm/s, where t is the thickness in nanometers.…”

“…The transmission electron microscopy (TEM) cross section of the flakes in a previous study revealed good quality of the flakes in the bulk, and hence point defects and dislocations are less likely [20]. Therefore, radiative or SRH (Shockley-Read-Hall, trapassisted) recombination are the more probable recombination routes, as was also deduced in a recent study on recombination dynamics in powdered tellurium [44]. Moreover, the authors found that radiative recombination is dominant with 98% radiative yield at room temperature.…”

“…The reported values at low temperature (77 K) range in the 10s of nanoseconds to microsecond regime, and the authors predicted the roomtemperature recombination time to be several orders smaller than at low temperature. A recent study on recombination dynamics in powdered tellurium obtained a few nanosecond lifetimes at room temperature using transient microwave conductivity with a minimum time resolution of 300 ps [44]. Our measurements are the first on thin film tellurium with subpicosecond time resolution.…”

Structures of Isolated Tellurium Chains Encapsulated Inside Carbon Nanotube

“…However, the LP orbitals overlap the antibonding (σ*) orbitals on adjacent chains. It has been pointed out that the overlap between LP and σ* orbitals through chains is the cause of the interchain interactions. ,− However, in many studies, interchain interactions have been thought to be van der Waals interactions. − The 1NN atomic distances between the chains are 3.467 and 3.478 Å for t-Se and t-Te, respectively, which are clearly smaller than twice the van der Waals radii, that is, 1.9 and 2.1 Å, respectively . The van der Waals interaction originates from dipole–dipole interactions and is thus weak.…”

Unconventional Thermally Activated Indirect to Direct Radiative Recombination of Electrons and Holes in Tin Disulfide Two-Dimensional van der Waals Material

“…The yellowish translucent flakes of SnS 2 were filled into a polyetheretherketone (PEEK) sample holder with a groove of 1 mm along the direction of high-energy electron irradiation, analogous to our previous study on Te. 30 The flakes were tightly pressed to fill the groove entirely. The sample holder was inserted into a copper waveguide cell suitable to perform microwave conductivity studies in the K aband (28−37 GHz), similar to previous studies.…”