Far-infrared observations of the galactic Cygnus region and Mars with a 60 cm diameter balloon-borne telescope

We have introduced secondary-mirror chopping in our balloon-borne far-infrared 60 cm Ø telescope equipped with He-cooled filters and a composite silicon bolometer with an NEP of 1.3 10^?14 W/Hz^1/2 for imaging, radiometry and spectroscopy of the Cygnus region at the wavelengths 80 μm, 130 μm and 310 μm. The modified system was flown on September 26/27, 1990 with a 380'000m³ hydrogen balloon at the CNES station at Aire/Adour, France. Observations were performed at a platform height of 39 km during 5 hrs. We made successful measurements on the complexes DR21 and S106 of the Cygnus region as well as on Mars at the wavelengths mentioned.     

Quantized IR properties reconfirmed in the CO and SiO surface oscillators present in the surface layer of A bamboo stem

From analysis of diffusion diagrams of CO stretching band (2500～2180 cm^?1), bending band (800～200 cm^?1) and SiO stretching band (1100～700 cm^?1) measured in a skin surface layer of a bamboo stem (silicate cellulose), azimuthal directions where oscillators oriented were shown as (?'=?-90) ?_N=a·N-b, with a=28.3, 2×28, 22.7, b=25, 47.5, 10. And N=1,2.....14, N=1, .....6. N=1,2.....16. The optical activity (reflection integral) was shown for the CO stret. band as M_i(N)=a·N+b, with a=21.8, b=42 and N =1,2.....9. And for the bending band as M_i(N)=a·N² +b·N?c, with a=1.87×10¹, b=3.73×10³, c=7.06×10² with N=1,2.....9. Six stepnized fine series in CO weak reflection bands were confirmed as, \(\bar v = A \cdot N^2 + B \cdot N + C (cm^{ - 1} )\) and \(\bar v_{C - 1} = A \cdot N^{1/2} + B (cm^{ - 1} )\) with N=1,2.....22. Mean values of the vibrational quantized states of the A, B and C-series in the SiO stretching weak band with R?1.0% were shown as, \(\overline {\Delta E} _m = 4.54 \times \bar v_{\text{m}}^{\text{2}} - 1.449 \times \bar v_m + 1.27 \times 10^7 \) (meV) with \(\bar v = E/hc\) .     

Infrared lattice bands of some pearls

From analysis of anisotropical lattice bands properties of ≈50 reflection spectra both of the CO stretching and bending bands measured from some pearl (Ca⁺⁺CO ₃ ^?? or Ca⁺⁺HCO ₃ ^?? layer) we discussed following subjects. i) Quantized properties present both in reflectivity and in energy. ii) classifications of the “Optical Activity”. iii) Polar distributions of the CO₃ oscillators in Ca⁺⁺CO ₃ ^?? surface mono-layer. iv) Force constants of these oscillators. v) Step variation of the dipolemoment and their influences to the degree of “Optical Activity”. vi) Two types of hysteresis loops of the values of Y_N (M_2Jbend (θ)/M_1Jstret. (θ)) derived from the oscillators which are at “innert-state”, at “weak active-state” and at “active-state”.     

Synthesis of Polythiophene/Poly(3,4-ethylenedioxythiophene) Nanocomposites and Their Application in Thermoelectric Devices

Polythiophene/poly(3,4-ethylenedioxythiophene) (PTh/PEDOT) nanocomposites with luminescent characteristics and high thermoelectric (TE) performance were successfully synthesized by two-step oxidative polymerization in aqueous medium. First, PTh nanoparticles (NPs) were synthesized by use of FeCl₃/H₂O₂ as catalyst/oxidant system with poly(4-styrene sulfonic acid) (PSSA) as surfactant. PTh/PEDOT nanocomposites were then synthesized by in situ oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT) on the surface of PTh NPs. The composition of the nanocomposites was controlled by varying the concentration of EDOT. Electron microscopy imaging and dynamic light scattering experiments confirmed the nanocomposites had a PTh core and a PEDOT shell/matrix. Finally, the TE performance of the PTh/PEDOT nanocomposites was investigated. The electrical conductivity and power factor of the nanocomposites were found to increase from 0.0001 S/cm to 475 S/cm and from 0.001 μW/mK² to 22.9 μW/mK², respectively, at the optimum PEDOT concentration.     

Properties of low-temperature (80-300° C) pyrolytic SiO2 on Si and InP

We report on a new low-temperature pyrolytic deposition technology for silicon dioxide. We present data characterizing the electrical and optical properties of this dielectric deposited on Si and InP substrates. The effects of thermal processing are also reported. Deposition of high-quality SiO₂ is achieved by reacting SiH₄ and O₂ at pressures of 2–12 Torr. Reactions occur by pyrolysis only, promoting stoichiometric SiO₂ deposition and good interfacial properties. No plasma- or photo-enhancement is required. Deposition is achieved at temperatures as low as 80° C, the lowest temperature ever reported for pyrolytic SiO₂ deposition. Rates as high as 65 Å/min at 100° C and 100-150 Å/min at 150-300° C are attained. The leakage current densities measured for both Si and InP MIS capacitors (e.g. 10^-9 Å/cm² for 150° C SiO₂) are two to six orders of magnitude lower than values reported for plasma- and photo-enhanced SiO₂ deposited at equivalent temperatures. The high-temperature integrity of this dielectric also makes it a promising annealing cap for group III-V compound semiconductors. Our annealing studies show that SiO₂-capped indium phosphide surfaces remain specular up to 850° C.     

Detection of minor constitutents of the stratosphere by far infrared emission spectroscopy

The far infrared (30–110 cm^?1) emission spectrum of the lower stratosphere has been measured from balloon altitudes with a high resolution (0.06 cm^?1) rapid-scanning Michelson interferometer on two flights in 1976. The quality and resolution of the spectra obtained from two altitudes have permitted a careful search for emission lines from environmentally important molecules such as HCl, NO₂, OH, H₂O₂, and CO, among the more prominent and well-known features due to H₂O, O₃ and O₂. Column densities have been determined for H₂O and O₃ and upper limit estimates have been made from tentative identifications of several other constituents. However, the large angular field of view observed by the instrument prevented the determination of concentration profiles from atmospheric limb scans to the horizon. The possible future directions of this technique are outlined on the basis of operating experience over a 6 year programme. The viability of this method of monitoring the concentrations of minor constituents in the stratosphere is discussed with respect to other equivalent techniques.     

Growth and characterization of Si doped vapor phase epitaxial GaAs for mesfet

This paper describes the Si-doping of GaAs that was grown using the AsCl₃:H₂:GaAs, Ga Chemical vapor deposition process. The doping sources were AsCl₃:SiCl₄ liquid solutions which proved to be highly reproducible for Si doping within the range, 1×1O¹⁶ to 2×10¹⁹ cm^?3. Incorporation of Si into the GaAs apparently occurs under near equilibrium conditions. This point is considered in detail and the consequences experimentally utilized to grow n, n+ bilayers using a single AsCl₃:SiCl₄ doping solution. Si impurity profiles based upon differential capacitance and SIMS data are presented. These can be very abrupt for n, n⁺ structures with order of magnitude changes occurring within 500 Å. For the 1×10₁₆ to 8×l0¹⁸ cm^?3 doped samples the mobilities at 78 and 298°K are comparable to the higher values reported for GaAs thin films grown by CVD. Power FET devices made from this material have demonstrated an output density of 0.86 watts/mm at 10 GHz.     

High- Purity inp grown by hydride vpe technique with impurity gettering by indium source and oxygen

Purification methods for vapor-grown InP layers have been investigated for the hydride (In/HCl/PH₃/H₂) process. The carrier concentration of non-doped InP layers was found to be decreased with a commensurate increase in mobility by increasing the indium source temperature and by introducing a small amount (a few ppm) of oxygen into the growth region. At 910 δC of In source temperature with 1.2 ppm oxygen, a 77 K mobility as high as 40,000 cm²/v.sec (3,480 cm²/v.sec at 300K) with a carrier concentration as low as 5x10¹⁴cm^?3 (8×10¹⁴cm^?3 at 300K) was obtained. Photoluminescence efficiency was also found to be improved by the above-mentioned two methods. Mass spectroscopy analysis of used In metal showed a few ppm impurity contamination, such as Sn, Fe and Cu, which were hardly detected in raw 6’9-purity In metal before the growth experiment. These results indicate that the In source has a gettering effect for impurities in input gases, mainly HC1 from a cylinder, and the effect was enhanced by increasing the In source temperature. The oxygen may play a role in the conversion to non-volatile oxides of residual impurities and hence a reduction in the impurity incorporation.     

Use of photocurrent-voltage characteristics of MOS structures to determine insulator bulk trapped charge densities and centroids

A new technique is described for determining the density and centroid of trapped space charge in the oxide layer of metal-oxide-semiconductor (MOS) structures. Photo-current-voltage (photo I-V) characteristics for both the metal-oxide and Si-oxide interfaces are used to determine the internal fields due to bulk trapped charge, and hence its density and centroid. Experimental examples for locating both positive and negative charge are presented. For negative charge, an Al-Si0₂-W-SiO₂-Si structure (MOWOS) with a layer of approximately 10¹⁴ W atoms/cm² deposited 80 Å from the Si-SiO₂ interface and charged by electronic internal photoemission is investigated. For positive charge, the location of trapped holes generated by 16.85 eV photons or x-rays in the SiO₂ layer of an MOS structure under a voltage bias is discussed. The photo I-V technique is compared to others in terms of its direct, rapid, minimally perturbing, low current, and low field characteristics.     

Arsenic silicide formation by oxidation of arsenic implanted silicon

Wet oxidations of (100) silicon implanted with an arsenic dose of 2 × 10¹⁶ cm⁻² and an energy of 30 keV were carried out in the temperature range between 600 and 900° C. The oxidation rate is increased on the arsenic implanted samples up to a factor of 2000 as compared to undoped samples. During these oxidations the arsenic suicide phase AsSi is precipitated at the oxide/silicon interface. After short oxidation times at 600° C, a continuous AsSi layer is found. It is dissolved during extended oxidation times and finally almost all As is incorporated in the oxide. After 900° C oxidations, substantial AsSi crystallites remain at the Si/SiO₂ interface. They are still observed up to the larg-est oxide thickness grown (2.3 μm). The AsSi phase and the distribution of the im-planted arsenic were analyzed by TEM, SIMS and XRF measurements.     

Pb1-xSnxTe epitaxial layers prepared by the hot-wall technique

Epitaxial layers of Pb_1-xSn_xTe were grown on polished-etched KCl substrates using the modified hot-wall technique. Four layers, each 5-30 μm thick, of area 5.5 × 5.5 mm² were simultaneously grown at growth rates of 0.3–4.8 μm/hr. A typical substrate temperature of 325°C , and baffle and source temperatures of 450-560°C were used. P-and n-type layers were obtained from stoichio-metric and metal-rich sources of (Pb_1-xSn_x)_1+δ Te_1-δ, 0.01≤δ ≤0.02, respectively. From metal-rich sources with 0<δ<0.01, the layers obtained were n-type at 300K but p-type at 77K. The layers became intrinsic between approximately 250K and 295K. Carrier concentrations of as-grown layers with 0≤x ≤0.26 were in the range of 10¹⁶-10¹⁷ /cm³ and mobilities were of the order of 10⁴ cm² /V-sec at 77K. Both n-and p-type layers were also obtained from metal-rich sources of δ = 0.01 by controlling the Te vapor pressure from a separate reservoir. With Te temperatures higher than the n-p turnover point of 240°C , p-type characteristics were obtained. Layers that were p-type at 77K grown with the Te temperatures near the n-p turnover point had the best mirror-like surfaces.     

p +-Si/nano-SiO2/n +-Si capacitor-based tunnel diode with negative differential resistance and a quartz resonator

To demonstrate the extending functionality of the simplest MOS (metal-oxide-semiconductor) capacitor, a structure with a p ⁺-Si/nano-SiO₂ heterojunction in which strongly degenerate n ⁺-Si is used instead of a metal electrode is considered. As a result, a tunnel diode with negative differential resistance and a quartz resonator is obtained. Its electrical characteristics are superior to those of the corresponding Esaki diode and are controlled not only by the Silicon doping level, but also by the SiO₂ thickness.     

High resolution molecular spectroscopy in the submillimeter region

Fourier Transform laboratory measurements have been carried out, for the first time in the 8–85 cm^?1 spectral region, with an unapodized resolution of 3.3. 10^?3 cm^?1 and a frequency accuracy of 2. 10^?4 cm^?1. Samples from spectra of several molecules namely: CO, O₃, H₂O₂, NO, NO₂, HNO₃, SO₂, H₂S, HOCL, NOCL, HNCO, ND₃ and AsH₃ are presented to show both the quality of the measurements and the type of information supplied by high resolution spectroscopy in the submillimeter region.     

Bi2SiO5 Doping Concentration Effects on the Electrical Properties of SrBi2Ta2O9 Films

In this paper, we investigated the microstructure and electrical properties of Bi₂SiO₅ (BSO) doped SrBi₂Ta₂O₉ (SBT) films deposited by chemical solution deposition. X-ray diffraction observation indicated that the crystalline structures of all the BSO-doped SBT films are nearly the same as those of a pure SBT film. Through BSO doping, the 2Pr and 2Ec values of SBT films were changed from 15.3 μC/cm² and 138 kV/cm of pure SBT to 1.45 μC/cm² and 74 kV/cm of 10 wt.% BSO-doped SBT. The dielectric constant at 1 MHz for SBT varied from 199 of pure SBT to 96 of 10 wt.% BSO-doped SBT. The doped SBT films exhibited higher leakage current than that of non-doped SBT films. Nevertheless, all the doped SBT films still had small dielectric loss and low leakage current. Our present work will provide useful insights into the BSO doping effects to the SBT films, and it will be helpful for the material design in the future nonvolatile ferroelectric memories.     

IR reflection spectra of the silicate surface layer of yellowed rice plant leaf

We have investigated the IR reflectional properties of the three-hold cytrogical surface layer (kutchikura layer on silicate layer n(SiO₂) on silicate cellulose layer C₆H₁₀Si_xO_y) and that of chlorophyll, a(C₅₅H₇₂M_gN₄O₅) etc., present in bladder's cells by using our experimental method. From analysis of three set of anisotropical reflection spectra assigned as due to CO, SiO and NC surface oscillators contained in the cytrogical cells and measured at 2500 2200 cm^?1, 1200 700 cm^?1 and at 700 200 cm^?1 regions, we have confirmed some important results. One is their quantized directional distributions that of the numbers of fine step spectrum and that of the reflection integrals of these spectra. Here, that of the NC oscillators were found to distribute in pentagonal directions relating to the molecular structure of chlorophyll. Second, we confirmed the pecularity of eight fine step-series measured in these sensitive spectra comparing with that of bamboo's seven series. Third, from analysis of the stepnized variation of the “reflection integrals”, we estimated the origin of this effect as which is presumably due to statistical, transfer of the 2p₄ valence electrons etc. in the oxygen atoms from C=O, Si=O double bonding side upto the shallower quantized states, E(N,J) which were formed softly around the and surface oscillators. And these surface oscillators were confirmed as to make photo-chemical reaction process by receiving energy higher than ～24 m eV especially under the illumination of sunshine etc.     

The performance of alloyed (CdS0.33Se0.67) quantum dots-sensitized TiO2 solar cell

The performance of alloyed CdS_0.33Se_0.67 quantum dots-sensitized solar cells (QDSSCs) is studied. Fluorine doped Tin Oxide (FTO) substrates were coated with 20nm-diameter TiO₂ nanoparticles (NPs). Presynthesized CdS_0.33Se_0.67 quantum dots (QDs) (radius 3.1 nm) were deposited onto TiO₂ nanoparticles (NPs) using direct adsorption (DA) method, by dipping for different times at ambient conditions. The FTO counter electrodes were coated with platinum, while the electrolyte containing I ^?/I ₃ ^? redox species was sand-wiched between the two electrodes. The characteristic parameters of the assembled QDSSCs were measured at different dipping times, under AM 1.5 sun illuminations. The maximum values of short circuit current density (J _sc) and conversion efficiency (η) are 1.115 mA/cm² and 0.25% respectively, corresponding 6h dipping time. Furthermore, the J _sc increases linearly with increasing the intensities of the sun light which indicates the linear response of the assembled cells.     

Methanol laser lines from torsionally excited co stretch states,and from OH-bend,CH3-rock,and CH3-deformation states

Using a quasi-CW CO₂ oscillator-amplifier combination with peak power 300 Watt, we have generated FIR laser emission in weak absorption bands of CH₃OH. 40 new lines are reported, and their wavelengths are measured with a relative accuracy of 5×10^?5. A total of 72 lines are assigned. 34 of these involve torsional n=1, 2, and 3 states of the CO stretch and the vibrational ground state. The remaining lines are associated with the CH₃-rock, OH-bend, and CH₃-deformation modes. The latter are located 1460 cm^?1 above the ground state, and are pumped by simultaneous vibrational excitation and torsional deexcitation.     

Specific features of the recombination loss of the photocurrent in n-TiN/p-Si anisotype heterojunctions

Photosensitive n-TiN/p-Si heterostructures are fabricated by reactive magnetron sputtering. The heterostructures generate an open-circuit voltage of V _oc = 0.4 V and a short-circuit current of I _sc = 1.36 mA/cm² under illumination at 80 mW/cm². An analysis of the light current-voltage characteristic and quantum-yield spectrum demonstrate that the poor photoelectric parameters are due to recombination in the base region of the heterojunction and to the formation of a high-resistivity SiO₂ layer on the surface of polycrystalline silicon, which fails to provide high-quality passivation of surface states.     

Ohmic contacts to InP-based materials induced by means of rapid thermal low pressure (metallorganic) chemical vapor deposition technique

A rapid-thermal-low-pressure-metallorganic-chemical-vapor-deposition (RT-LPMOCVD) technique was executed in order to deposit non-semiconductor thin layer materials, necessary for producing metal contact to InP-based microelectronic devices. Silicon dioxide (SiO₂) films were deposited onto InP substrates in rapid thermal cycles, using O₂ and 2% diluted SiH₄ in Ar, with very fast growth kinetics and low activation energy. The SiO₂ film exhibited excellent properties, such as refractivity index, density, internal stress, and wetp-etch rates. The SiO₂ films were dry etched in a given pattern to allow for the formation of a small metal contact to the InP-based material, onto which the SiO₂ layer was deposited. Subsequently, titanium-nitride (TiN _x ) thin films were deposited onto the InP substrate through rapid thermal deposition cycles, using a tetrakis (dimethylamido) titanium (DMATi) metallorganic liquid source as the precursor for the process, with fast kinetics. The deposited TiN _x films had a stoichiometric structure and contained nitrogen and titanium in a ratio close to unity, but incorporated a large amount of carbon and oxygen. The film properties, such as resistivity (40–80 μΩ·mm) and stress (compressive; ?0.5 to ?2.0×10⁹ dyne·cm^?2), were studied in addition to an intensive investigation of its microstructure and morphology, and their performance as an ohmic contacts while deposited ontop?In_0.53Ga_0.47As material (Zn doped 1.2×10¹⁸ cm^?3).     

Generation of sum-frequency sideband using 964 GHz HCN laser and 70 GHz klystron radiation

Continuosly tunable submillimeter radiation above 1 THz has been generated by sum-frequency mixing of HCN laser radiation (second strongest transition at 964.3 GHz) with that of klystron (70 GHz) in the Schottky barrier diode used as the non-linear element. Generated radiation was sufficiently strong to allow the high resolution frequency measurement of 9_9,1 ← 8_8,0 transition in³²S¹⁶O.