Band-tail Formation and Band-gap Narrowing Driven by Polar Optical Phonons and Charged Impurities in Atomically Resolved III-V Semiconductors and Nanodevices

Sarangapani, Prasad; Chu, Yuanchen; Charles, James; Klimeck, Gerhard; Kubis, Tillmann

doi:10.1103/physrevapplied.12.044045

Cited by 26 publications

(18 citation statements)

References 57 publications

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“…the Urbach parameter increases with incoherent scattering of electrons on charged impurities (as also observed in Ref. 31). The scattering rates are proportional to the imaginary retarded scattering self-energies (Σ R ) 73 .…”

Section: Simulation Approachsupporting

confidence: 66%

“…The imaginary part of the retarded self-energy provides information about the scattering rate of the electrons 73 . The real part of the retarded self-energies yields an energy shift of electronic states 31,74 . Since this work focuses on the Urbach parameter only, the real part of all retarded scattering self-energies is ignored.…”

Section: Simulation Approachmentioning

confidence: 99%

“…Different scattering mechanisms can interfere with each other and impact the electronic density of states which is hard to estimate without detailed calculations. 31,51,52 . This is further complicated by the strong dependence of electronic and scattering properties in TMD systems on the number of atomic layers and their environment 48,53,54 .…”

mentioning

confidence: 99%

“…Therefore, this work predicts Urbach parameters for MoS 2 , WS 2 and WSe 2 layer systems as a function of layer thickness, temperature, doping concentration, and oxide type (comprising Al 2 O 3 , HfO 2 , SiO 2 and h-BN) with DFT-based quantum transport calculations 55,56 for electronic Green's functions including scattering on various types of phonons, charged impurities and remote scattering on oxide phonons with NEMO5. 31,57,58 . We delineate the contribution of different scattering mechanisms towards the Urbach parameter and gain insight into its dependence on layer thickness and oxide type.…”

mentioning

confidence: 99%

“…All calculations in this work are based on the non-equilibrium Green's function (NEGF) implementation of NEMO5. NEGF is well suited to analyze Urbach parameters 31,59 since it is a method of choice to predict electronic behavior when incoherent scattering and coherent quantum effects are equally important.…”

mentioning

confidence: 99%

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Band tail formation in mono and multilayered transition metal dichalcogenides: A detailed assessment and a quick-reference guide

Sarangapani,

Charles,

Kubis

2021

Preprint

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Transition metal dichalcogenides (TMDs) are promising candidates for a wide variety of ultrascaled electronic, quantum computation, and optoelectronic applications. The exponential decay of electronic density of states into the bandgap, i.e. the band tail has a strong impact on the performance of TMD applications. In this work, the band tails of various TMD monolayer and multilayer systems when placed on various dielectric substrates is predicted with density functional theory based nonequilibrium Green's functions. Nonlocal scattering of electrons on polar optical phonons, charged impurities and remote scattering on phonons in the dielectric materials is included in the self-consistent Born approximation. The band tails are found to critically depend on the layer thickness, temperature, doping concentration and particularly on the chosen dielectric substrate. The underlying physical mechanisms are studied in high detail and an analytical interpolation formula is given to provide a quick-reference for Urbach parameters in MoS 2 , WS 2 and WSe 2 .

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Section: Simulation Approachsupporting

confidence: 66%