We found the easy and efficient synthesis method of vertically aligned ultralong multiwalled nanotubes using iron chloride powder. The 2.1-mm-long bulk can be grown by conventional thermal chemical vapor deposition on bare quartz surface with single gas flow acetylene for 20min. In addition to high growth rate, carbon is easily spun into yarn pulling it out, present also provides coating ability as a new functionality this nanomaterial.

The PbTe-SnTe superlattice was expected to be a type-II where the valence band edge of SnTe is higher than conduction PbTe. To ascertain structure, we prepared by hot wall epitaxy, and performed its Hall measurement. Magnetic-field-dependent relatively small coefficients were obtained for superlattices, which show coexistence free electrons holes in superlattice. superlattices increased with annealing time owing gradual disappearance coexistence. Diffusion Sn studied using x-ray diffraction analysis.

We measured the Seebeck coefficient of P-doped ultrathin silicon-on-insulator (SOI) layers with thicknesses 2–100 nm. The dependence on impurity concentration was investigated, and shown to be in good agreement that bulk Si for SOI above 6 In addition, it found decrease increasing concentration, which is usually observed semiconductor materials. However, doping levels 3.5×1019 cm-3, increase. This likely due influence an band.

Theoretical calculations of the Seebeck coefficients bulk PbTe and based superlattices were described in framework Boltzmann equation, taking into account temperature dependent band gaps, nonparabolicity, anisotropy effective masses. It is shown that gradient along superlattice layer works more effectively on enhancement thermoelectric figure merit than normal to layer. Calculated compared experimental values for n-type PbTe, p-type EuTe/PbTe superlattices. The coefficient was higher PbTe....

Abstract Managing heat dissipation is a necessity for nanoscale electronic devices with high-density interfaces, but despite considerable effort, it has been difficult to establish the phonon transport physics at interface due “complex” layer. In contrast, amorphous/epitaxial expected have almost no layer lack of lattice mismatch strain and less associated defects. Here, we experimentally observe extremely-small thermal resistance per unit area amorphous-germanium sulfide/epitaxial-lead...

Pb1−xEuxTe films were prepared by hot-wall epitaxy, evaporating PbTe, Eu, and Te from the same quartz-tube furnace onto BaF2 (111) substrates. Good crystalline obtained preparing in excess vapor. Dependence of energy band gaps lattice constants Pb1−x EuxTe on EuTe content was measured through optical absorption, x-ray diffraction, microanalysis. Temperature dependence gap also measured. Single-phase with Eg ≤0.83 eV x≤0.26 obtained. Derivatives respect to x(dEg/dx) 3.5 at 300 K 4.5 77 up...

Optical transmission spectra of PbTe/Pb1−xEuxTe (x=0.05) superlattices were measured at 300 K. The prepared on thick Pb1−xEuxTe buffers grown KCl (100) substrates using the hot wall epitaxy technique. Clear steplike absorptions corresponding to interband electron transitions between subbands (n=1,2,3 n=1,2,3) observed for first time superlattice. experimental absorption edges agreed very well with theoretical ones calculated assuming conduction-band offset is equal that valence band.

Lattice-matched PbSnTe-PbTeSe multiple quantum well lasers fabricated by hot wall epitaxy have been developed. Though the system is a type I′ superlattice, using band bending due to doping, laser operation like I superlattices has achieved for first time. The worked in pulsed up 204 K with 6 μm radiation (cw at 130 6.6 radiation).

SnTe-based films and superlattices (SLs) were prepared their electrical properties measured. A EuTe/SnTe SL exhibited a hole mobility of 2720 cm2/V s, which is the highest value reported for any semiconductor material at room temperature. The SnEuTe film also high in contrast to PbEuTe system. These are explained terms band offsets heterojunction decrease number Sn vacancies. In addition, SnTe/PbSe SnTe/PbS SLs with thin SnTe layers displayed n-type conduction Seebeck coefficients comparable...

High efficiency laser operation with output power exceeding 2 W was obtained for vertical external-cavity PbS based IV-VI compound surface emitting quantum-well structures. The showed external quantum as high 16%. Generally, mid-infrared III-V or II-VI semiconductor utilizing interband electron transitions are restricted by Auger recombination and free carrier absorption. is much lower in the semiconductors, free-carrier absorption significantly reduced an optically pumped structure...

Pb1−xSrxS/PbS double-heterostructure stripe contact lasers were prepared for the first time using a hot-wall expitaxy technique. The laser operated up to 245 K pulsed (2.97 μm) and 174 cw, which are highest operating temperatures ever reported any semiconductor diode around 3 μm. In this letter preparation properties of Pb1−xSrxS presented.

Three kinds of superlattices consisting good lattice-matched and -mismatched materials (Pb0.76Sn0.24Te-PbSe0.10Te0.90, Pb0.76Sn0.24Te-PbTe, Pb0.76Sn0.24Te-PbSe0.18Te0.82 superlattices) were prepared by a hot-wall epitaxy their high-angle x-ray diffractions measured. Sn-diffusion effects on the satellite structure are studied it was found that Sn diffusion increases lattice distortion for Pb0.76Sn0.24Te-PbSe0.10Te0.90 superlattice lattice-mismatched superlattice, other hand, decreases...

Theoretical and experimental studies on Seebeck effect in EuTe∕PbTe superlattices were performed. calculations, which take into account temperature dependent band gap, nonparabolicity, anisotropy of effective masses the PbTe conduction band, performed framework Boltzmann equation enhancement coefficient short-period grown [100] direction was predicted. The with few monolayers EuTe prepared KCl (100) substrate an enhanced observed these as expected by theoretical calculations.

The SnTe, Sn1−xEuxTe and Sn1−xSrxTe (x<0.06) films were prepared by hot wall epitaxy. ternary alloy in cation rich condition had hole concentration around 1×1019 cm−3 with high mobility exceeding 2000 cm2/V s at room temperature. Optical transmission spectra also measured the temperature range from 100 to 400 K compared theoretical calculations. of SnTe simulated successfully assuming bumped band edge structures. A inversion model was proposed for systems, optical model.

Photoluminescence measurements of ZnTe-ZnSe superlattices prepared on GaAs (100) substrates by hot wall epitaxy method were carried out. Free- and bound-exciton lines due to the interband transitions observed for first time. Absorption spectra reflection transmission modes measured confirm exciton lines. A theoretical calculation based envelope function scheme is presented explain structure dependence photoluminescence data, taking strain effects into account.

High quality ZnTe-ZnSe strained-layer superlattices grown on GaAs (001) substrates have been obtained by the hot wall epitaxy technique through introducing ZnTe and ZnSe buffers. Raman scattering from folded longitudinal acoustic phonons was observed. High-angle satellite reflection peaks due to Cu Kα1 Kα2 radiations were clearly resolved in x-ray diffraction patterns, these patterns can be almost interpreted a simple step model. The effect of buffer layer strain superlattice is evaluated...

GaN films were prepared by hot wall epitaxy on sapphire (0001) substrates from Ga and NH3 sources. Growth characteristics of the investigated reflection high energy electron diffraction (RHEED) x-ray measurements, effects initial layers film growth are discussed. High quality with streak RHEED patterns obtained when grown a layer predeposition its nitridation surface nitrided substrates.