Stable ultra-thin CdTe crystal: a robust direct gap semiconductor

İyikanat, Fadıl; Akbalı, Barış; Kang, Jun; Senger, R. T.; Selamet, Yusuf; Şahin, Hasan

doi:10.1088/1361-648x/aa957e

Cited by 7 publications

(8 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This agrees with the DFT results of Ref. 45. Positive frequencies throughout the BZ ensure the dynamical stability of monolayer CdTe.…”

Section: Resultssupporting

confidence: 92%

“…We compute DFT bandgap values for bulk and monolayer CdTe of 0.18 and 1.2 eV, respectively. To correct the bandgaps, we perform a rigid shift of occupied and unoccupied electronic bands to match with the experimental value of 1.5 eV for bulk and with calculations using the Heyd-Scuseria-Ernzerhof (HSE) functional of 2.13 eV for monolayer CdTe [45,46]. While the shift modifies the electronic gap sizes visible in Figs.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Charge-carrier thermalization in bulk and monolayer CdTe from first principles

Yadav,

Pauly,

Trushin

2019

Preprint

View full text Add to dashboard Cite

While cadmium telluride (CdTe) thin films are being used in solar cell prototyping for decades, the recent advent of two-dimensional (2D) materials challenges the fundamental limit for thickness of conventional CdTe layers. Here, we report our theoretical predictions on photocarrier dynamics in an ultimately thin (about 1 nm) CdTe slab. It corresponds to a layer that is just a single unit cell thick, when the bulk parent crystal in the zinc blende phase is cleaved along the [110] facet. Using an ab-initio method based on density functional theory (DFT) and the Boltzmann equation in the relaxation time approximation (RTA), we determine the thermalization time for charge carriers excited to a certain energy for instance through laser irradiation. Our calculations include contributions arising from all phonon branches in the first Brillouin zone (BZ), thus capturing all relevant inter-and intraband carrier transitions due to electron-phonon scattering. We find that the photocarrier thermalization time is strongly reduced, by one order of magnitude for holes and by three orders of magnitude for electrons, once the CdTe crystal is thinned down from the bulk to a monolayer. Most surprisingly, the electron thermalization time becomes independent of the electron excess energy up to about 0.5 eV, when counted from the conduction band minimum (CBM). We relate this peculiar behavior to the degenerate and nearly parabolic lowest conduction band that yields a constant density of states in the 2D limit. Our findings may be useful for designing novel CdTe-based optoelectronic devices, which employ nonequilibrium photoexcited carriers to improve the performance.

show abstract

“…This agrees with the DFT results of Ref. 45. Positive frequencies throughout the BZ ensure the dynamical stability of monolayer CdTe.…”

Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Charge-carrier thermalization in bulk and monolayer CdTe from first principles

Yadav,

Pauly,

Trushin

2019

Preprint

View full text Add to dashboard Cite

show abstract

“…Since it is an easy and effective method, strain is often used to manipulate fundamental properties of ultra-thin materials. 20,[52][53][54] Hence, the strain effect on the structural, magnetic, and electronic properties of monolayer α-RuCl 3 are investigated in this section. As seen in Fig.…”

Section: Strain Applicationmentioning

confidence: 99%

Tuning electronic and magnetic properties of monolayer α-RuCl₃ by in-plane strain

et al. 2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…Other 2D Te-based materials such as the group IIIA/IVA-Te (e.g., InTe, SnTe, and GaTe) have also been extensively investigated as promising thermoelectric materials. Bulk CdTe and CdTe 2 are semiconductors with band gaps of 1.50 (direct) and 1.08 eV (indirect), respectively. CdTe thin films have been widely used in solar cell prototyping .…”

Section: Introductionmentioning

confidence: 99%

Bonding Heterogeneity Inducing Low Lattice Thermal Conductivity and High Thermoelectric Performance in 2D CdTe₂

Wan

Gao

Huang

et al. 2022

ACS Appl. Energy Mater.

View full text Add to dashboard Cite

materials have emerged as a broad platform for exploring promising thermoelectric materials. Motivated by the fabrication of diverse artificially designed Tebased 2D materials with high thermoelectric performance, here, we predicted 2D hexagonal CdTe and pentagonal CdTe 2 for potential thermoelectric materials, using the particle swarm optimization (PSO) method combined with density functional theory. CdTe and CdTe 2 show predicted direct/indirect band gaps of 1.82 and 1.96 eV, respectively. Chemical bonding analysis revealed that all the Te atoms in CdTe are coupled through uniform ionic bonding. CdTe 2 exhibits bonding heterogeneity, arising from weak the Cd− Te ionic bonding and strong Te−Te covalent bonding. Based on Boltzmann transport theory, we found that the bonding heterogeneity in CdTe 2 favors low lattice conductivity. The calculated lattice thermal conductivity of CdTe 2 is 0.33 Wm −1 K −1 at 300 K, which was contributed by the weaker coupling between acoustic and optical phonon modes, low group velocities of the acoustic modes, and high lattice anharmonicity. On the other hand, the occupied π* 5p , π 5p , and σ 5p bondings in Te−Te pairs significantly facilitate the electrical conductivity and enhance the Seebeck coefficient of p-type CdTe 2 . The low thermal conductivity and high power factor in CdTe 2 give rise to a high thermoelectric performance at low temperature. Our findings should encourage the exploration of 2D materials for thermoelectric applications with strong bonding heterogeneity.

show abstract

Stable ultra-thin CdTe crystal: a robust direct gap semiconductor

Cited by 7 publications

References 58 publications

Charge-carrier thermalization in bulk and monolayer CdTe from first principles

Charge-carrier thermalization in bulk and monolayer CdTe from first principles

Tuning electronic and magnetic properties of monolayer α-RuCl₃ by in-plane strain

Bonding Heterogeneity Inducing Low Lattice Thermal Conductivity and High Thermoelectric Performance in 2D CdTe₂

Contact Info

Product

Resources

About

Stable ultra-thin CdTe crystal: a robust direct gap semiconductor

Cited by 7 publications

References 58 publications

Charge-carrier thermalization in bulk and monolayer CdTe from first principles

Charge-carrier thermalization in bulk and monolayer CdTe from first principles

Tuning electronic and magnetic properties of monolayer α-RuCl3 by in-plane strain

Bonding Heterogeneity Inducing Low Lattice Thermal Conductivity and High Thermoelectric Performance in 2D CdTe2

Contact Info

Product

Resources

About

Tuning electronic and magnetic properties of monolayer α-RuCl₃ by in-plane strain

Bonding Heterogeneity Inducing Low Lattice Thermal Conductivity and High Thermoelectric Performance in 2D CdTe₂