Thermal property of binary tetrahedral semiconductors

In this paper we present an expression relating the lattice thermal expansion coefficient α_L (10⁻⁶ K⁻¹) for the A^IIIB^V and A^IIB^VI semiconductors with the product of ionic charges (Z₁Z₂), melting temperature (T_m) and nearest neighbor distance d (Å). The lattice thermal expansion coefficient of these compounds exhibit a linear relationship when plotted on a log–log scale against the melting temperature (T_m), but fall on different straight lines according to the ionic charge product of the compounds. A good agreement has been found between the experimental and calculated values of the lattice thermal expansion coefficient for A^IIIB^V and A^IIB^VI semiconductors.     

Cohesive energy of zincblende (A<Superscript>III</Superscript>B<Superscript>V</Superscript> and A<Superscript>II</Superscript>B<Superscript>VI</Superscript>) structured solids

In this paper we present an expression relating the cohesive energy (E _coh in kcal/mol) of A^IIIB^V and A^IIB^VI semiconductors with the product of ionic charges (Z ₁ Z ₂) and nearest-neighbour distance d (Å). The cohesive energy values of these solids exhibit a linear relationship when plotted on a log-log scale against the nearest-neighbour distance d (Å), but fall on different straight lines according to the ionic charge product of the solids. A good agreement has been found between the experimental and calculated values of the cohesive energy of A^IIIB^V and A^IIB^VI semiconductors.     

Fianite: A multipurpose electronics material

Fianite-zirconium dioxide, stabilized by yttrium (YSZ) has a unique combination of physical and chemical properties that made it a very promising material for a wide range of applications. In this work, we consider the use of fianite as a bulk substrate and buffer layer for A ^III B ^V epitaxy, and as an antireflection and protective coating for photo detectors and solar cells.     

Consistency of crystal-lattice parameters and thermalexpansion coefficients in five-component heterostructures based on compounds AIIIBV

The possibility of expansion of the limits of variation in the width of the forbidden band in five component solid solutions of compounds A^IIIB^V with consistency of crystallattice parameters and thermal-expansion parameters of the binary substrate and epitaxial layer is analyzed. Possible regions, and the corresponding character, of variation in composition in five-component solid solutions of compounds A_IIIB^V with simultaneous consistency of the crystal-lattice parameters and thermal-expansion coefficients with the binary substrates are identified.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 59–64, January, 1989.     

The Growth of P-type TlGaSe2(1−x) S2x Single Crystals

TlGaSe_2(1–x) S_2x single crystals were grown by the modified Bridgman-Stockbarger method in our crystal growth laboratory. A^IIIB^III C₂ ^VI compounds are formed of elements from vertical groups of the periodic table (group III: Tl, Ga, In; group VI: Se, S, Te) and are classified into two types. The first type has a layer structure: TlGaSe₂, TlGaS₂ and TlInS₂. The second type has a chained structure: TlInSe₂, TlInTe₂ and TlGaTe₂. None of the grown crystals had cracks and voids on the surface. The freshly cleaved crystals had a mirror-like surface and there was no need for mechanical or chemical polishing treatments. By the hot probe technique, we have found that the crystals were of p-type. The ingots produced were single crystalline and the useful region of single crystal was 90% with steps of 10 K if changes were small, and with steps of 3 and 5 K if changes were large in the direct and indirect band gaps energies. The direct and indirect band gaps for TlGaSe_2(1–x)S_2x samples were calculated as a function of temperature.     

The theory of infrared dispersion of light in crystals with chalcopyrite lattice

The low-frequency dielectric tensor is calculated for A^IIB^IVC ₂ ^V and A^IB^IIIC ₂ ^VI crystals in terms of the long-wave frequencies of lattice vibrations, corresponding to various orientations of the wave vector. The qualitative shape of the spectrum of mechanical polaritons is obtained. The coefficient of light reflection is calculated as a function of the frequency and direction of propagation for a CdGeP₂ crystal.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 39–43, June, 1978.     

Calculational method for isoparametric compositions and the width of the forbidden band of five-component solid solutions based on AIII BV compounds

A method is presented for the thermodynamic calculation of the isoparametric composition and of the width of the forbidden band of five-component solid solutions of A^III B^V compounds. Calculation has been performed of compositions and of the width of the forbidden band of five-component solid solutions whose lattice is commensurate with binary substrates A^III B^V. The necessity of taking into account the effect of ordering on the width of the forbidden band of a solid solution is shown.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 41–47, July, 1989.     

High frequency and static dielectric constants of zinc blende structured solids

A correlation is presented for the high frequency ε_∞ and static ε_o dielectric constants of A^IIB^{V I} and A^IIIB^V semiconductors with the zinc blende structure. The high frequency ε_∞ and static ε_o dielectric constants can be represented by an empirical linear relation that is a simple function of melting temperature T_m, atomic volume Ω and product of ionic charges (Z₁Z₂). Values of high frequency ε_∞ and static ε_o dielectric constants of A^IIB^{V I} and A^IIIB^V zinc blende semiconductors exhibit a linear relationship when plotted against the k_BT_m/Ω (k_B=Boltzmann’s constant), but fall on two straight lines according to the product of ionic charges of the compounds. The calculated results are compared with available experimental data and previous calculations based on phenomenological models.     

Rotational Analysis of the 1–4 Band of the B 2Σ+–X 2Σ+ System of 14C16O+

ABSTRACT

High-resolution emission spectrum of the 1–4 band of the B ²Σ⁺–X ²Σ⁺ transition of ¹⁴C¹⁶O⁺ was observed for the first time by conventional emission spectroscopy. The band spectrum was excited in a water-cooled Geissler lamp filled with commercial gaseous carbon monoxide enriched in about 80% of the radiocarbon ¹⁴C. A rotational analysis has been carried out and obtained molecular constants have been merged with previously published data for the B ²Σ⁺–A ²Π_i and A ²Π_i–X ²Σ⁺ transitions. The principal equilibrium constants for the ground X ²Σ⁺ state obtained from this work are ω_e = 2121.7726(98), ω_e x _e = 13.9055(27), B _e = 1.815290(30), α_e = 1.6594(33) × 10^?2, and γ_e = ? 0.377(73) × 10^?4 cm^?1. Also, presently known experimental equilibrium molecular constants of the X ²Σ⁺ states of the CO⁺ isotopic molecules are summarized and isotopic dependence of the B _e and ω _e constants is discussed.     

Research on AIIIBV materials for optoelectronics in the Institute of Physics and Technology of Materials

Conclusions This paper summarizes the work done on A^IIIB^V materials for optoelectronics in the Institute of Physics and Technology of Materials in the last 5–6 years. Part of this work has an original mark on it, part of it follows recognized ways opened else-where. The author expresses his belief that viable roots have been established for stabilizing and for opening up new directions in this institute and in Romania for the remarkable important A^IIIB^V research.Invited talk at the International Conference on Radiative Recombination and Related Phenomena in III–V Compound Semiconductors, Prague, 4–7 October, 1983.     

Relaxation of electron-ionic processes in intercalated layer and chain crystals of AIIIBIIICVI2-type semiconductors

The results of a study of the intercalation effect on electric and photoelectric properties and on low-temperature structural phase transitions in layer and chain crystals of A^IIIB^IIIC^VI₂ -type semiconductors are presented.     

Rotational analysis of the 0–9, 0–10 and 0–11 bands of theA 2II u -X 2II g band system of (16O18O)+

High-resolution spectra of the 0–9, 0–10 and 0–11 bands of theA ²II _u —X ²II _g system of (¹⁶O¹⁸O)⁺ ion have been studied for their rotational structure. This study enables a direct determination of the Λ-doubling parameters of theA ²II _u andX ²II _g states. The model of ‘pure precession’ explains, though not entirely, the Λ-doubling of theX ²II _a state as arising out of its interaction with theB ² Σ _g ⁻ state. The Λ-doubling in theA ²II _u state was found insignificant.     

Theoretical Studies of the Electron Paramagnetic Resonance and Optical Spectral Data for Vanadium(IV) Ion in Yttrium Aluminum Garnet Crystal

Four spin-Hamiltonian parameters (g factors g _// and g _⊥ and hyperfine structure constants A _// and A _⊥) and two optical spectral band positions for vanadium(IV) (V⁴⁺) ion in the tetrahedral Al³⁺ site of yttrium aluminum garnet (Y₃Al₅O₁₂) crystals are calculated from the (third-order) perturbation theory method (PTM) and complete diagonalization (of energy matrix) method (CDM). Both methods are based on the cluster approach. The calculated results from both methods coincide and reasonably agree with the experimental values. The defect structure of V⁴⁺ center (which is different from the corresponding structure in the host crystal) in Y₃Al₅O₁₂ crystal is also obtained from the calculation.     

Bond-stretching and bond-bending force constant of binary tetrahedral (AB and AB) semiconductors

In this Letter we present the two expressions relating the bond-stretching force constant (α in N/m) and bond-bending force constant (β in N/m) for the A^IIIB^V and A^IIB^VI semiconductors with the product of ionic charges (Z₁Z₂) and nearest neighbor distance d (Å). Interatomic force constants of these compounds exhibit a linear relationship when plotted on a log-log scale against the nearest neighbor distance d (Å), but fall on different straight lines according to the ionic charge product of the compounds. A fairly good agreement has been found between the observed and calculated values of the α and β for binary tetrahedral semiconductors.     

Electrolytic coloration and spectral properties of OH- and Cu-codoped NaCl crystals

OH⁻- and Cu⁺-codoped NaCl crystals are colored electrolytically by using a pointed anode and a flat cathode at various temperatures and under various voltages. Absorption and fluorescence spectral properties of colored crystals are investigated. Absorption, excitation and fluorescence spectra reveal existence of V₂, V₂^m, V₃, OH⁻, U, U_A, O²⁻–V_a⁺, O₂⁺, Cu⁺, Cu⁰, Cu⁻ and OH⁻-perturbed Cu⁺ color centers in colored crystals. Formations of color centers are explained.     

Defect Structure and EPR Parameters of the Cu2+Center in MNB Ternary Glasses

The electron paramagnetic resonance (EPR) parameters (g factors g _//, g _⊥ and hyperfine structure constants A _//, A _⊥) for 15MgO-15Na₂O-69B₂O₃ (MNB):Cu²⁺ ternary glasses were calculated based on the high-order perturbation formulae of 3d⁹ ion in a tetragonal symmetry. From the calculations, the defect structures of MNB:Cu²⁺ ternary glasses were obtained and a negative sign for A _// and A_⊥ for the Cu²⁺ center is suggested in the discussion.     

AsO+同位素离子X2∑+和A2∏电子态的多参考组态相互作用方法研究

采用包含Davidson修正多参考组态相互作用(MRCI)方法结合价态范围内的最大相关一致基As/aug-cc-pV5Z和O/aug-cc-pV6Z, 计算了AsO⁺ (X²∑⁺)和AsO⁺(A²∏)的势能曲线. 利用AsO⁺离子的势能曲线在同位素质量修正的基础上, 拟合出了同位素离子⁷⁵As¹⁶O⁺和⁷⁵As¹⁸O⁺的两个电子态光谱常数. 对于X²∑⁺态的主要同位素离子⁷⁵As¹⁶O⁺, 其光谱常数R_e, ω_e, ω_ex_e, B_e和α_e分别为 0.15770 nm, 1091.07 cm^-1, 5.02017 cm^-1, 0.514826 cm^-1和0.003123 cm^-1; 对于A²∏态的主要同位素离子⁷⁵As¹⁶O⁺, 其T_e, R_e, ω_e, ω_ex_e, B_e和α_e分别为5.248 eV, 0.16982 nm, 776.848 cm^-1, 6.71941 cm^-1, 0.443385 cm^-1和0.003948 cm^-1. 这些数据与已有的实验结果均符合很好. 通过求解核运动的径向薛定谔方程, 找到了J=0时AsO⁺(X²∑⁺)和AsO⁺(A²∏)的前20个振动态. 对于每一振动态, 还分别计算了它的振动能级、转动惯量及离心畸变常数, 并进行了同位素质量修正, 得到各同位素离子的分子常数. 这些结果与已有的实验值非常一致. 本文对于同位素离子⁷⁵As¹⁶O⁺(X¹∑⁺), ⁷⁵As¹⁸O⁺(X¹∑⁺), ⁷⁵As¹⁶O⁺(A¹∏)和⁷⁵As¹⁶O⁺(A¹∏)的光谱常数和分子常数属首次报导.     

Ab initio study of the Ar–CS2(V1B2) intermolecular potential surface: effect of van der Waals interaction on the emission of CS2 molecule

In this work, the excited state intermolecular potential energy surface of the Ar–CS₂(V¹B₂) van der Waals complex was evaluated for the first time. The calculation of more than 4000 single-point interaction energies for the complex using an equation-of-motion coupled-cluster model with single and double substitutions level of theory with extended basis set involving bond functions has been performed. After fitting the interaction energies to analytical functions, the emission spectra of the Ar–CS₂(V¹B₂) complex related to the different stationary points on the potential energy surface were calculated. It was seen that the intensity and the position of the emission spectra are dependent on the orientation of the Ar atom around the bent excited CS₂ and the distance between two components. The information about the structural parameters of the complex related to the global minimum was obtained under the pseudodiatomic approximation with assistance of ab initio potential. The presented investigation could be useful for further theoretical and experimental studies of Ar–CS₂(V¹B₂) complex.     

The ClO4 radical: a theoretical study on ground and excited states

In agreement with previous studies, the ground state of ClO₄ has been confirmed to be X²B₁. Vertical excitation energies and oscillator strengths were calculated by MRCI methods for doublet and quartet states of ClO₄. The highest oscillator strength was found for 1²A₁ at 2.95 eV. This state has been identified as the upper state seen by Kopitzky and co-workers in the absorption spectrum of ClO₄. Two higher states, 2²A₁ and 3²A₁, at 4.19 and 8.12 eV, respectively, also have relatively high oscillator strengths. Rydberg states start at about 9.5 eV. Geometry optimizations were performed by DFT and CCSD(T) methods. After extensive testing, the B3LYP density functional, together with the 6-311 + G(3df) basis set were chosen for calculations. Optimized geometries of seven excited states were obtained. The adiabatic excitation energy of 1²A₁ (2.40 eV) agrees closely with the observed band origin at 2.46 eV. Three excited states have one or two imaginary vibrational modes. Electron affinity and heat of formation of ClO₄ agree with literature values. None of the quartet states was found to be stable.