Assessment of optical phonons in BeTe, BexZn1-xTe, p-BeTe epilayers and BeTe/ZnTe/GaAs (001) superlattices

Talwar, Devki N.; Becla, P.

doi:10.1007/s00339-022-05819-z

Cited by 3 publications

(26 citation statements)

References 72 publications

(146 reference statements)

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“…Two different theoretical schemes are frequently employed for assessing the structural, phonon and electronic traits of the perfect/imperfect materials: (a) microscopic methods [19][20][21]79], which start with ionic potentials screened by electron gas for determining the optical, electronic and phonon properties, and (b) macroscopic techniques [69][70][71][72][73][74][75][76], which employ phenomenological models for attaining the lattice dynamics of perfect materials as well as impurity-induced vibrational characteristics. In the former methods, the interatomic forces of perfect/imperfect materials are normally evaluated using selfconsistent density functional theory (SC-DFT) for comprehending the structural, optical, and phonon properties by employing commercially available ABINIT software V9.10.…”

Section: Theoretical Sectionmentioning

confidence: 99%

“…In Section 3.5, we briefly outline the theory of a realistic RIM to study the lattice dynamics of perfect zb InAs and InN. An ATM-GF [73][74][75][76] approach requiring appropriate perturbation models for isolated defects is adopted for simulating the impurity vibrational modes of Si + III donors and Si − V , Mg − III and C − V acceptors in InAs and InN [53][54][55][56][57]. The calculated results are discussed and compared/contrasted against the existing FTIR and RSS (Section 4) data.…”

Section: Theoretical Sectionmentioning

confidence: 99%

“…To comprehend the lattice dynamical traits of perfect bulk InAs and InN materials, we have adopted a realistic RIM [77]. The vibrational properties of isolated donor and acceptor defects in InAs and InN are studied by using the ATM-GF theory [73][74][75][76]. The significance of these two methodologies has been discussed in several review articles and monographs [69][70][71][72][73][74][75][76].…”

Section: Lattice Dynamics Of Perfect/imperfect Inas and Innmentioning

confidence: 99%

“…The vibrational properties of isolated donor and acceptor defects in InAs and InN are studied by using the ATM-GF theory [73][74][75][76]. The significance of these two methodologies has been discussed in several review articles and monographs [69][70][71][72][73][74][75][76]. Hence, the discussion (Section 4.4) of presenting our results on the impurity vibrational modes for both isolated Si +…”

Section: Lattice Dynamics Of Perfect/imperfect Inas and Innmentioning

confidence: 99%

“…For IRR simulations, the standard deviations χ (≡≤5 × 10 −3 ) were attained for accurately obtaining the necessary phonon mode parameters of each sample. Appropriate dielectric dispersions were meticulously determined by invoking Kramers-Krönig analyses to attain frequency-dependent [69][70][71][72][73][74][75][76] complex dielectric functions ∼ ε(ω) and refractive indices ∼ n(ω). A two-phonon mode behavior is expected in the InAs 1−x N x alloy epifilms where the effects of the InP substrate cannot be ignored.…”

Section: Introductionmentioning

confidence: 99%

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Phonon Characteristics of Gas-Source Molecular Beam Epitaxy-Grown InAs1−xNx/InP (001) with Identification of Si, Mg and C Impurities in InAs and InN

Talwar,

Yang,

Lin

2023

Crystals

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The lattice dynamical properties of dilute InAs1−xNx/InP (001) epilayers (0 ≤ x ≤ 0.03) grown by gas-source molecular beam epitaxy were carefully studied experimentally and theoretically. A high-resolution Brüker IFS 120 v/S spectrometer was employed to measure the room-temperature infrared reflectivity (IRR) spectra at near-normal incidence (θi = 0). The results in the frequency range of 180–500 cm−1 revealed accurate values of the characteristic In-As-like and In-N-like vibrational modes. For InAs1−xNx alloys, a classical “Drude–Lorentz” model was constructed to obtain the dielectric functions ε~ω in the far IR regions by incorporating InAs-like and InN-like transverse optical ωTO modes. Longitudinal optical ωLO phonons were achieved from the imaginary parts of the simulated dielectric loss functions. The theoretical results of IRR spectra for InAs1−xNx/InP (001) epilayers using a multi-layer optics methodology provided a very good agreement with the experimental data. At oblique incidence (θi ≠ 0), our study of s- and p-polarized reflectance (Rs,p(ω)) and transmission (Ts,p(ω)) spectra allowed the simultaneous perception of the ωTO and ωLO phonons of the InAs, InN and InAs0.97N0.03 layers. Based on the average t-matrix Green’s function theory, the results of local vibrational modes for light SiIn+ donors and SiAs−, CAs− acceptors in InAs were found in good agreement with the existing Raman scattering and infrared spectroscopy data. InInN, however, the method predicted an in-band mode for the MgIn− acceptor while projecting an impurity mode of the SiIn+ donor to appear just above the maximum ωmaxInN[≡595 cm−1] phonon frequency region. In InAs1−xNx/InP (001) epifilms, the comparison of reflectivity/transmission spectra with experiments and the predictions of impurity modes for isoelectronic donor and acceptor impurities in InAs and InN can be valuable for appraising the role of defects in other technologically important semiconductors.

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Section: Theoretical Sectionmentioning

confidence: 99%

Section: Theoretical Sectionmentioning

confidence: 99%

Section: Lattice Dynamics Of Perfect/imperfect Inas and Innmentioning

confidence: 99%

Section: Lattice Dynamics Of Perfect/imperfect Inas and Innmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Phonon Characteristics of Gas-Source Molecular Beam Epitaxy-Grown InAs1−xNx/InP (001) with Identification of Si, Mg and C Impurities in InAs and InN

Talwar,

Yang,

Lin

2023

Crystals

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Evaluating Interfacial Layer Thickness from Phonon Characteristics of Novel Carbon-Based Strained Superlattices

Talwar¹,

Becla²

2023

Preprint

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Systematic results of lattice dynamical calculation are reported for the novel (SiC)m/(GeC)n superlattices (SLs) by exploiting a modified-linear chain model (M-LCM) and a realistic rigid-ion- model (RIM). By employing the bond polarizability method in the framework of M-LCM, we have simulated Raman intensities for the graded (SiC)10-D/(Si0.5Ge0.5C)D/(GeC)10-D/(Si0.5Ge0.5C)D SLs by carefully integrating interfacial layer thickness D (≡ 0, 1, 2, 3 monolayers (MLs)). The variation of D has initiated considerable up (down) shifts of GeC-, (SiC)-like Raman peaks in the middle of the optical phonon frequency region. With D = 3 MLs, the maximum energy shift (by ~ 47 cm-1) of SiC-like modes has caused substantial changes in the Raman intensity profiles linked to the localization of atomic displacements at the interfacial transition regions. This effect can be considered as a vital tool for authenticating the interfacial structures in technologically important SLs. By using a RIM, we have reported SL phonon dispersions along the growth [001] as well as in the plane [100], [110] perpendicular to the growth. Our simulations of phonons in the acoustic mode region have not only confirmed the formation of minigaps at the zone center and zone edges but also provided evidence of anti-crossing and phonon confinement. Besides examining angular dependence of zone-center optical modes, we have also discussed phonon folding, confinement and anisotropic behavior in (SiC)m/(GeC)n SLs.

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Evaluating Phonon Characteristics by Varying the Layer and Interfacial Thickness in Novel Carbon-Based Strained-Layer Superlattices

Talwar,

Becla

2023

Solids

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Systematic results of lattice dynamical calculations are reported as a function of m and n for the novel (SiC)m/(GeC)n superlattices (SLs) by exploiting a modified linear-chain model and a realistic rigid-ion model (RIM). A bond polarizability method is employed to simulate the Raman intensity profiles (RIPs) for both the ideal and graded (SiC)10-Δ/(Si0.5Ge0.5C)Δ/(GeC)10-Δ/(Si0.5Ge0.5C)Δ SLs. We have adopted a virtual-crystal approximation for describing the interfacial layer thickness, Δ (≡0, 1, 2, and 3 monolayers (MLs)) by selecting equal proportions of SiC and GeC layers. Systematic variation of Δ has initiated considerable upward (downward) shifts of GeC-(SiC)-like Raman peaks in the optical phonon frequency regions. Our simulated results of RIPs in SiC/GeC SLs are agreed reasonably well with the recent analyses of Raman scattering data on graded short-period GaN/AlN SLs. Maximum changes in the calculated optical phonons (up to ±~47 cm−1) with Δ = 3, are proven effective for causing accidental degeneracies and instigating localization of atomic displacements at the transition regions of the SLs. Strong Δ-dependent enhancement of Raman intensity features in SiC/GeC are considered valuable for validating the interfacial constituents in other technologically important heterostructures. By incorporating RIM, we have also studied the phonon dispersions [ωjSLq→] of (SiC)m/(GeC)n SLs along the growth [001] as well as in-plane [100], [110] directions [i.e., perpendicular to the growth]. In the acoustic mode regions, our results of ωjSLq→ have confirmed the formation of mini-gaps at the zone center and zone edges while providing strong evidences of the anti-crossing and phonon confinements. Besides examining the angular dependence of zone-center optical modes, the results of phonon folding, confinement, and anisotropic behavior in (SiC)m/(GeC)n are compared and contrasted very well with the recent first-principles calculations of (GaN)m/(AlN)n strained layer SLs.

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Assessment of optical phonons in BeTe, BexZn1-xTe, p-BeTe epilayers and BeTe/ZnTe/GaAs (001) superlattices

Abstract: z. The Version of Record is the version of the article after copy-editing and typesetting, and connected to open research data, open protocols, and open code where available. Any supplementary information can be found on the journal website, connected to the Version of Record.

Cited by 3 publications

References 72 publications

Phonon Characteristics of Gas-Source Molecular Beam Epitaxy-Grown InAs1−xNx/InP (001) with Identification of Si, Mg and C Impurities in InAs and InN

Phonon Characteristics of Gas-Source Molecular Beam Epitaxy-Grown InAs1−xNx/InP (001) with Identification of Si, Mg and C Impurities in InAs and InN

Evaluating Interfacial Layer Thickness from Phonon Characteristics of Novel Carbon-Based Strained Superlattices

Evaluating Phonon Characteristics by Varying the Layer and Interfacial Thickness in Novel Carbon-Based Strained-Layer Superlattices

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