Opto-electronic properties of CuAlO2

CuAlCO₂ is a p-type semiconductor with an average hole mobility of $\text{1.1 × 10}{}^{\mathrm{?7}}\text{m}{}^2\text{Vs}$. From photoelectrochemical measurements its bandgap is found to be indirect allowed at 1.65 eV; other interband transitions are at 2.3 and 3.5 eV. The valence band is made up mainly from Cu-3d wave functions and lies 5.2 eV below the vacuum level.     

Electrons and holes in HgTe and Hg0.82Cd0.18Te with controlled deviations from stoichiometry

The deviations from the stoichiometric composition of HgTe and Hg_0.82Cd_0.18Te crystals have been controlled by heat treatment under Hg vapor pressure. The magnetic field dependence of the Hall coefficient always shows the presence of two different sets of electrons and one set of holes. A low mobility electron is shown to belong to the conduction band. Vapor pressure dependence of hole concentration in HgTe shows that the concentration of nonstoichiometric defects decreases with increasing Hg vapor pressure, but the hole concentration is always higher than the electron concentration. In the case of Hg_0.82Cd_0.18Te, the electron concentration exceeds the hole concentration at high Hg vapor pressures. The dependence of the conduction band electron mobility in HgTe upon carrier density shows that the scattering by holes and impurities is predominant. In Hg_0.82Cd_0.18Te, however, optical phonon scattering is dominant when the deviation from stoichiometry is small and the effect of residual impurities can be neglected, and scattering by holes is dominant when the hole concentration is over $\text{10}{}^{17}\text{cm}{}^3$.     

Electron and hole conductivity in CuInS2

Single crystals of CuInS₂ have been grown from the melt and annealed in In or S to produce good n- or p-type conductivity, respectively. Two donor levels, one shallow and one deep (0.35 eV), and one acceptor level at 0.15 eV are identified. The hole-mobility data are best fitted with an effective mass $\text{m}{}_{\mathrm{<mtext>p</mtext>}}\text{1?1.3m}{}_{\mathrm{e}}$, which can be explained by simple, two band $\text{k}$. $\text{p}$ theory if the valence band has appreciable d character. Above 300°K, the hole mobility falls rapidly, evidently due to multiband conduction and/or interband scattering between the nondegenerate and degenerate valence bands. The conduction band mobility appears to be dominated, in many samples, by large concentrations ( >10¹⁸cm^?3) of native donors and acceptors, which are closely compensated.     

Mixed conduction in Cr-doped GaAs

Hall-effect and magnetoresistance measurements have been carried out in GaAs : Cr as functions of magnetic field strength (B = 0–18kG) and temperature (T = 125–420°K). Independent solutions for the mobilities, μ_n and μ_p, and the carrier concentrations, n and p, are obtained from the basic mixed-conductivity equations. These quantities, as well as the intrinsic carrier concentration, n_i are then calculated as a function of temperature for one sample, and subsequent analysis yields the following values in the range T = 360–420°K: an acceptor (presumably Cr) energy E_A = 0.69±0.02eV (from the valence band); the bandgap energy E_g = E_g0 + αT, with E_go = 1.48±0.02eV, $\text{α ? 3.2 × 10}{}^{\mathrm{?4}}\text{eV}\text{°}\text{K}$; $\text{μ}{}_{\mathrm{n}}\text{= 2700± 100}\text{cm}{}^2\text{V}\text{sec}$, decreasing slightly with temperature; = 350± 50 $\text{cm}{}^2\text{V sec}$; and an acceptor-to-donor concentration ratio, itN_A/N_D?8. The electron mobility appears to be limited by neutral impurity scattering, with N_A ? 2 × 10¹⁶cm^?3. Several other samples were also investigated but as a function of temperature only (at B = 0). At room temperature both positive (p-type) and negative (n-type) Hall coefficients were observed.     

Hole mobility in evaporated layers of As2S3.CdI2

The hole drift mobility in As₂S₃.CdI₂ has been determined using Spear's method. The room-temperature value is 10^?4$\text{cm}{}^2\text{Vs}$, the activation energy 0.2 eV. The hole yield appears to be controlled by geminate recombination.     

Intensity measurements,self-broadening coefficients,and rotational intensity distribution for lines of the oxygen B band at 6880 Å

Quantitative measurements of intensities and half-widths were made for individual rotational lines of the atmospheric oxygen B band. The total band intensity, as derived from the line intensity measurements, is 40·8±0·6 cm^?1km^?1atm^?1 STP. As had been previously found in this laboratory for the oxygen A band, the relative line intensities conform closely to the rotational distribution calculated by either Schlapp or by Watson. The line half-widths at half-intensity were determined for oxygen self-broadening for the ${}^{\mathrm{P}}\text{Q}$ and ${}^{\mathrm{P}}\text{P}$ branch lines and for a few ${}^{\mathrm{R}}\text{Q}$ and ${}^{\mathrm{R}}\text{R}$ branch lines near the band origin, and were found to vary from 0·064 cm^?1atm^?1 at J′ = 1 to 0·042 cm^?1atm^?1 at J′ = 25.     

Temperature,injection level,and frequency dependences of the luminescence in lightly - and heavily-doped CdTe:In

The temperature dependence, injection level dependence, and modulation frequency response of cathodoluminescence have been measured in Te-rich CdTe:In for materials with In concentrations ranging from 3 × 10¹⁵cm^?3 to 1 × 10¹⁸cm^?3. In lightly-doped material, the 80 K luminescence shows sharp band-edge emission near 1.57 eV and a broad impurity-defect band near 1.4 eV. As temperature increases, the 1.4 eV band quenches out, leaving only the band-edge emission. In heavily-doped material, the band- edge emission is absent and the 80 K luminescence shows only the 1.4 eV band. As the temperature increases from 80 K to 300 K, the 1.4 eV band does not quench out but rather undergoes a complex evolution into a long tail on the band-edge emission which begins to appear at approximately 140 K. At a temperature of 200 K, where the luminescence of the heavily-doped material consists of a broad but structured band approximately 0.2 eV in width, frequency response measurements indicate that band-to-band transitions contribute to the high-energy part of the broad luminescence while the remainder of the band results from slower transitions. The frequency and temperature dependences suggest that the luminescence involves an impurity level that has merged with a band edge at an In concentration of $\text{1 × 10}{}^{18}\text{cm}{}^3$. We interpret this behavior as suggesting that the 1.4 eV luminescence in Te-rich CdTe:In results from a partially-forbidden transition between conduction band and a deep acceptor level rather than from an intracenter type of transition.     

UV-induced double injection in α-sulfur single crystals

The I–V characteristics of the UV-induced double injection of carriers into sulfur single crystals are reported. These characteristics display a quadratic behavior as a function of the electric field up to E≈7×10³$\text{Volts}\text{cm}$ where it changes to a cubic law dependence. The V² branch can be accounted for by means of the one carrier space charge limited current. The cube law dependence arises as a result of the recombination limited two-carrier injection according to the model of Lampert and Mark. We estimate values for the common lifetime τ = 4.8×10^?3 sec, and the trap modulated mobility of holes $\text{μ}{}_{\mathrm{<mtext>h</mtext>}}\text{θ}{}_{\mathrm{<mtext>h</mtext>}}\text{=8.9×10}{}^{\mathrm{?6}}\text{cm}{}^2\text{V sec}$.     

Preparation and semiconducting properties of Th3As4

The resistivity, thermoelectric power and Hall constant in the temperature range of 78–830 K were determined for polycrystalline Th₃As₄ samples obtained by annealing thin thorium slabs in arsenic vapour. The samples examined were n-type semiconductors with a carrier concentration ranging from 1.0 × 10¹⁸cm^?3 to 2.8 × 10¹⁸ cm^?3 for which the effective mass was found to be equal to 0.55–0.76m₀. The Hall mobility, about 450cm²V^?1s^?1 at room temperature, obeys a $\text{T}{}^{\mathrm{<mtext>?3</mtext><mtext>2</mtext>}}$ law at high temperatures. On the basis of the electrical measurements the forbidden gap of Th₃As₄ was found to be equal to 0.43 eV.     

Pressure spectroscopy of impurity states in GaSb(Se)

Galvanomagnetic effects and Shubnikov-de Haas oscillations are studied in monocrystalline GaSb(Se) samples ($\text{n}{}_{\mathrm{<mtext>se</mtext>}}\text{= 10}{}^{17}\text{?10}{}^{18}\text{cm}{}^{\mathrm{?3}}$) in magnetic fields up to 50 kOe at temperatures 0,07 K ?T?300 K under pressures p?12 kbar. Pressure spectroscopy has been used to determine the density of states in impurity bands and to investigate the anomalies of the transport properties of Γ-electrons near mobility edge ε_c on both metal and insulator sides.     

Analysis of the Raman spectrum of SF6

The Raman active fundamentals ν₁(A1g), ν₂(Eg), ν₅(F2g), and the overtone 2ν₆ of SF₆ have been investigated with a higher resolution and the band origins were estimated to be: ν₁ = 774.53 cm^?1, ν₂ = 643.35 cm^?1, ν₅ = 523.5 cm^?1, and 2ν₆ = 693.8 cm^?1. Raman and infrared data have been combined for estimation of several anharmonicity constants. The ν₆ fundamental frequency is calculated as 347.0 cm^?1. From the analysis of the ν₂ Raman band, the following rotational constants of both the ground and upper states have been calculated:

$\text{B}{}_0\text{= 0.09111 ± 0.00005}\text{cm}{}^{\mathrm{?1}}\text{; D}{}_0\text{= (0.16±0.08)10}{}^{\mathrm{?7}}\text{cm}{}^{\mathrm{?1}}$

;

$\text{B}{}_2\text{= 0.09116 ± 0.00005}\text{cm}{}^{\mathrm{?1}}\text{; D}{}_2\text{= (0.18±0.04)10}{}^{\mathrm{?7}}\text{cm}{}^{\mathrm{?1}}$

.     

Intensity measurements and self-broadening coefficients in the γ band of O2 at 628 nm using intracavity laser-absorption spectroscopy (ICLAS)

Quantitative measurements of intensities and widths were made for individual rotational lines of the atmospheric oxygen $\text{b}{}^1\text{Σ}{}_{\mathrm{g}}{}^{\mathrm{+}}\text{(ν′ = 2) ← X}{}^3\text{Σ}{}_{\mathrm{g}}{}^{\mathrm{?}}\text{(ν″ = 0)}$ γ band by using a recently developed, highly sensitive, intracavity laser-absorption spectroscopic technique (ICLAS) at 300 torr m. The total band intensity derived from the line intensities is $\text{1.26 ± 0.05}\text{cm}{}^{\mathrm{?1}}\text{km}{}^{\mathrm{?1}}\text{atm}{}^{\mathrm{?1}}$ (STP). Self-broadening collision coefficients for the ^PP and ^PQ branch lines have been determined from the absorption line width and were found to vary from 0.055 cm^?1 atm^?1 at N″ = 1 to 0.037 cm^?1 atm^?1 at N″ = 27.     

High-resolution infrared spectrum of the ν2 and ν8 bands of CH2D2

A high-resolution infrared spectrum of methane-d₂ has been measured in the C-D stretching band region (2025–2435 cm^?1). Rotational structures of the ν₂ and ν₈ bands have been assigned by use of the ASSIGN-diagram method, and the c-type Coriolis interaction between ν₂ and ν₈ has been analyzed. The band origins, ν₂ = 2203.22 ± 0.01 cm^?1 and ν₈ = 2234.70 ± 0.01 cm^?1, the rotational constants and the centrifugal distortion constants for the two bands, and the Coriolis coupling constant, $\text{∥;ξ}{}_{28}{}^{\mathrm{c}}\text{∥; = 0.182 ± 0.015}\text{cm}{}^{\mathrm{?1}}$, have been determined.     

Study of the photoluminescence spectrum in high purity CdTe

In this work, a study of the photoluminescence produced by a high purity sample of n-type CdTe of $\text{?}\text{N}{}_{\mathrm{<mtext>D</mtext>}}\text{?}\text{N}{}_{\mathrm{<mtext>A</mtext>}}\text{? < 10}{}^{14}$ impurities per cm³ was done at several temperatures, varying from 10 to 35 K. Several sharp lines were observed in the spectral region between 1.5 to 1.6 eV, plus the well-known 1.4 eV band with several well-defined structures on it. The observed temperature behaviour of the line positions, linewidths and relative intensities allowed us to establish the presence of a new transition, located at 10 K 21.3 meV below in energy from the free exciton (FE) line, as well as its first phonon replica. Its nature seems to be transitions originating from the conduction band to an acceptor level, 32 meV above the valence band. These two lines appear at the same position where previous works had reported the first and second phonon replicas of the FE. A scheme of impurity level is proposed to explain the observed transitions in terms of previously established levels and this new acceptor level.     

Search for 4n IN π− double charge exchange reactions with heavy nuclei

A search for the existence of the tetraneutron has been made using the double charge exchange reaction $\text{π}{}^{\mathrm{?}}\text{+}{}^{208}\text{Pb}\text{→}{}^4\text{n + π}{}^{\mathrm{+}}\text{+}$ residuals for ⁴n production and the capture process in the same target, ${}^{208}\text{Pb}\text{+}{}^4\text{n}\text{→}{}^{212}\text{Pb}\text{+ γ}$, for the ⁴n detection. No event has been found, giving an upper limit for the product of the production cross section σ_p, the detection cross section σ_d and the ⁴n lifetime τ. Assuming 10^?18 ≦ τ ≦ 10^?9 sec it follows that σ_pσ_dτ ≦ 2.5 × 10^?65cm⁴ sec with 90 % confidence, and for $\text{τ ≧ 10}{}^{\mathrm{?9}}\text{sec}\text{, σ}{}_{\mathrm{<mtext>p</mtext>}}\text{σ}{}_{\mathrm{<mtext>d</mtext>}}\text{≦ 2.5 × 10}{}^{\mathrm{?56}}\text{cm}{}^4$ with 90 % confidence. The magnitude of this value is comparable to the experimental limit of the ⁴He(π^?, π⁺)⁴n cross section.     

The laser magnetic resonance spectrum of the NCO radical at 5.2 μm

Lines in the ν₃ (“antisymmetric” stretch) fundamental of the NCO radical in the $\text{X}\text{?}{}^2\text{Π}$ state were studied by CO laser magnetic resonance. The observations were assigned to P and R lines in the vibration-rotation band and lead to a precise determination of the vibrational interval and the anharmonic correction to the rotational constant: ν₃ = 1920.60645(19) cm^?1, α₃ = 0.003338(21) cm^?1. A single transition in the hot band (011)-(010), ${}^2\text{Δ}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{-}{}^2\text{Δ}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ was detected. This observation is used to determine the origin of the hot band as 1907.11892(20) cm^?1, i.e., the anharmonicity parameter x₂₃ = ?13.48753(28) cm^?1.     

276-nm absorption band system of m-dichlorobenzene: Rotational band contour analysis

The 276-nm absorption band system (${}^1\text{B}{}_2\text{←}{}^1\text{A}{}_1$) of m-dichlorobenzene was photographed under high resolution. The electronic origin band (0, 0) and a band at (0 + 380) cm^?1 were subjected to rotational “band contour” analysis. As a result, it is found that the origin band has a type A band contour and that at (0 + 380) cm^?1 exhibits a type B band contour. The band contour analysis also yields an accurate determination of the excited state parameters, viz., A′ = 0.0911 ± 0.0003, B′ = 0.02852 ± 0.00005, and C′ = 0.02175 ± 0.00001 cm^?1. A model geometry for the molecule m-DCB in its first excited singlet state has been proposed.     

Dielectronic satellite spectra from dense laser-produced plasmas

The Lyman-α and adjacent dielectronic satellite lines have been observed in the spectra from laser-irradiated solid targets. In a carbon plasma from a planar target, the relative intensity of the $\text{2p}{}^2{}^3\text{P?1s2p}{}^3\text{P}$ satellite line of C(V) increases as a function of electron density in the range 8 × 10¹⁹ to 2 × 10²⁰ cm^?3. As analysis of a series of imploded microballoon experiments indicates that the $\text{2p}{}^2{}^3\text{P?1s2p}{}^3\text{P}$ and $\text{2s2p}{}^3\text{P?1s2s}{}^3\text{S}$ satellite radiation of Si(XIII) increases for electron densities 1 × 10²²?2 × 10²³ cm^?3. The satellite intensity distributions have been numerically simulated using a rate equation model. It is shown that the carbon and silicon satellite data may be interpreted in a consistent manner, and the extension to higher atomic numbers Z and higher electron densities is considered.     

The rotational analysis of the 1Π-X 1Σ+ system at 649.5 nanometers of zirconium oxide

A red-degraded band head, normally badly overlapped by the gamma system, $\text{A}{}^3\text{Φ}\text{- X′}{}^3\text{Δ}$, of zirconium oxide, appears in emission spectra of zirconium arcs and in absorption spectra of S-type stars and of frozen rare gas matrices containing zirconium. The emission band has been examined at high-resolution with the aid of separated zirconium isotopes. Identification of the band as 0-0 of a ${}^1\text{Π}\text{- X}{}^1\text{Σ}{}^{\mathrm{+}}$ system of zirconium oxide is confirmed by rotational analysis where the following constants (cm^?1) are obtained for ⁹⁰Zr¹⁶O:

$\text{B}{}_0\text{′(R,P) = 0.40142 D}{}_0\text{′(R,P) = 3.51 × 10}{}^{\mathrm{?7}}$

$\text{B}{}_0\text{′(Q) = 0.40166 D}{}_0\text{′(Q) =3.52 × 10}{}^{\mathrm{?7}}$

$\text{B}{}_0\text{″ = 0.42263 D}{}_0\text{″ =3.19 × 10}{}^{\mathrm{?7}}$

$\text{ν}{}_0\text{= 15383.81s}$

The Λ-type doubling in the ¹Π state and the question of whether $\text{X}{}^1\text{Σ}{}^{\mathrm{+}}$ or $\text{X′}{}^3\text{Δ}$ is the true ground state of ZrO are discussed.