Band splitting and plurality of excitons in Ruddlesden-Popper metal halides

The organic-inorganic interactions within the hybrid lattice of two-dimensional Ruddlesden-Popper metal halides(RPMH) have consequences on the structural and electronic properties of the material. Such interactions have been primarily investigated through a library of organic cations, keeping the inorganic lead halide lattice component intact. Here, we demonstrate that the role of the organic-inorganic interactions in electronic processes can also be effectively manipulated by the metal cation, particularly moving from heavier lead to lighter tin. We perform in-depth spectroscopic and theoretical analysis of prototypical tin-based RPMH, in which we identify the presence multiple resonances in the optical spectra, which correspond to distinct exciton series. We show that the higher energy excitonic series are composed of electronic transitions from a lower lying valence band which originates from variations in the coordination geometries of the metal halide octahedra induced by subtle changes in the organic-inorganic interactions. Our studies indicate that the deformation induced splitting of the carrier bands is ubiquitous to the Ruddlesden-Popper architectures, although the splitting energies are substantially higher in the tin based systems.

TEMPERATURE DEPENDENCE OF HEAT CAPACITY OF ALUMINIUM, COPPER, SILICON, MAGNESIUM AND ZINC AND COMPARISON WITH DEBYE THEORY

The results of comparison of heat capacity of aluminum, copper, silicon, magnesium and zinc with Debye's theory depending on temperature are given in the paper. It was revealed that the main components of the heat capacity of metals are the lattice component; is a component due to thermal expansion and is an electronic contribution. It is proposed that when creating the theory of heat capacity, it is necessary to take into account the anharmonicity of the oscillations of atoms in the nodes of the crystal lattice and the change in Debye temperature.

Studies of Thermal Anisotropy in 4H-, 6H-SiC Bulk Single Crystal Wafers by Photopyroelectric (PPE) Method

Thermal anisotropy in 4H-, and 6H-SiC bulk single crystal wafers was studied by the PPE method. The thermal diffusivities of the [1-100] and [11-20] orientations (^c-axis) samples were higher than those of the [0001] orientation (//c-axis) samples. Moreover, the thermal anisotropies of the lattice component and the carrier component were analyzed by Raman measurement.

Doping Dependence Of The Thermal Conductivity Of Hydride Vapor Phase Epitaxy Grown n-GaN/Sapphire (0001) Using A Scanning Thermal Microscope

We have measured the doping concentration dependence of the room temperature thermal conductivity (κ) of two series of n-GaN/sapphire (0001) fabricated by hydride vapor phase epitaxy (HVPE). In both sets κ decreased linearly with log n, the variation being about a factor two decrease in κ for every decade increase in n. κ ≈ 1.95 W/cm-K was obtained for one of the most lightly doped samples (n = 6.9×1016 cm−3), higher than the previously reported κ ≈ 1.7-1.8 W/cm-K on lateral epitaxial overgrown material [V.A. Asnin et al, Appl. Phys. Lett. 75, 1240 (1999)] and κ ≈ 1.3 W/cm-K on a thick HVPE sample [E.K. Sichel and J.I. Pankove, J. Phys. Chem. Solids 38, 330 (1977)]. The decrease in the lattice component of κ due to increased phonon scattering from both the impurities and free electrons outweighs the increase in the electronic contribution to κ.

Doping Dependence of the Thermal Conductivity of Hydride Vapor Phase Epitaxy Grown n-GaN/Sapphire (0001) Using a Scanning Thermal Microscope

We have measured the doping concentration dependence of the room temperature thermal conductivity (κ) of two series of n-GaN/sapphire (0001) fabricated by hydride vapor phase epitaxy (HVPE). In both sets n decreased linearly with log n, the variation being about a factor two decrease in κ for every decade increase in n. κ ≈ 1.95 W/cm-K was obtained for one of the most lightly doped samples (n = 6.9×1016 cm−3), higher than the previously reported κ ≈ 1.7-1.8 W/cm-K on lateral epitaxial overgrown material [V.A. Asnin et al, Appl. Phys. Lett. 75, 1240 (1999)] and κ κ 1.3 W/cm-K on a thick HVPE sample [E.K. Sichel and J.I. Pankove, J. Phys. Chem. Solids 38, 330 (1977)]. The decrease in the lattice component of κ due to increased phonon scattering from both the impurities and free electrons outweighs the increase in the electronic contribution to κ.

Deviation from Matthiessen's Rule and Lattice Thermal Conductivity of Alloys

The purpose of this note is to point out that the difference in the ideal -electronic thermal conductivity between an alloy and a pure metal can be estimated from the corresponding difference in the ideal electrical resistivity, using the Wiedemann-Franz law. This allows the separation of the thermal conductivity into an electronic and a lattice component to be made with greater confidence, particularly at liquid oxygen temperatures.

Thermal and Electrical Conductivities of Iron, Nickel, Titanium, and Zirconium at Low Temperatures

Measurements are reported of the thermal and electrical conductivities of iron, nickel, titanium, and zirconium down to 2 �K. These indicate that thermal conduction in pure iron and nickel is almost completely electronic. Titanium and zirconium exhibit an appreciable lattice component of thermal conduction. In the case of titanium this lattice component varies as T1.5.

The Lattice Component of the Thermal Conductivity of Metals and Alloys

Makinson's (1938) theory of the lattice component of the thermal conductivity of metals and alloys, when limited at low temperatures by interaction with the conduction electrons, is re-examined, and the magnitude of the lattice conductivity is related to the electronic thermal conductivity at low temperatures, thus avoiding uncertainties in the theory at high temperatures. The result depends on whether transverse lattice waves can interact with the electrons.