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 4 publications

(26 citation statements)

References 72 publications

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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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Deep Ultraviolet Excitation Photoluminescence Characteristics and Correlative Investigation of Al-Rich AlGaN Films on Sapphire

Feng,

Tian,

Zhang

et al. 2024

Nanomaterials

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AlGaN is attractive for fabricating deep ultraviolet (DUV) optoelectronic and electronic devices of light-emitting diodes (LEDs), photodetectors, high-electron-mobility field-effect transistors (HEMTs), etc. We investigated the quality and optical properties of AlxGa1−xN films with high Al fractions (60–87%) grown on sapphire substrates, including AlN nucleation and buffer layers, by metal–organic chemical vapor deposition (MOCVD). They were initially investigated by high-resolution X-ray diffraction (HR-XRD) and Raman scattering (RS). A set of formulas was deduced to precisely determine x(Al) from HR-XRD data. Screw dislocation densities in AlGaN and AlN layers were deduced. DUV (266 nm) excitation RS clearly exhibits AlGaN Raman features far superior to visible RS. The simulation on the AlGaN longitudinal optical (LO) phonon modes determined the carrier concentrations in the AlGaN layers. The spatial correlation model (SCM) analyses on E2(high) modes examined the AlGaN and AlN layer properties. These high-x(Al) AlxGa1−xN films possess large energy gaps Eg in the range of 5.0–5.6 eV and are excited by a DUV 213 nm (5.8 eV) laser for room temperature (RT) photoluminescence (PL) and temperature-dependent photoluminescence (TDPL) studies. The obtained RTPL bands were deconvoluted with two Gaussian bands, indicating cross-bandgap emission, phonon replicas, and variation with x(Al). TDPL spectra at 20–300 K of Al0.87Ga0.13N exhibit the T-dependences of the band-edge luminescence near 5.6 eV and the phonon replicas. According to the Arrhenius fitting diagram of the TDPL spectra, the activation energy (19.6 meV) associated with the luminescence process is acquired. In addition, the combined PL and time-resolved photoluminescence (TRPL) spectroscopic system with DUV 213 nm pulse excitation was applied to measure a typical AlGaN multiple-quantum well (MQW). The RT TRPL decay spectra were obtained at four wavelengths and fitted by two exponentials with fast and slow decay times of ~0.2 ns and 1–2 ns, respectively. Comprehensive studies on these Al-rich AlGaN epi-films and a typical AlGaN MQW are achieved with unique and significant results, which are useful to researchers in the field.

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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 4 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

Deep Ultraviolet Excitation Photoluminescence Characteristics and Correlative Investigation of Al-Rich AlGaN Films on Sapphire

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