Thermoelectric power in crystalline boron

The thermoelecric power of mono-crystalline beta-boron (purity >99.9995%, room-temperature resistivity 5 × MegaOhm cm), measured in the dark, increased from 305 to a maximum of 700 µV/K, and then fell to 650 µV/K, respectively, at T = 190, 345, and 435 K. The observed temperature dependence explained assuming two components in the boron conductivity: a p-type conduction in the valence band, and an n-type conduction of electrons hopping in an impurity band

Interdiffusion of thin chromium and gold films deposited on silicon

The backscattering technique was used to study the interdiffusion process of Cr and Au films deposited on Si substrates. The results indicate that Au diffuses in Cr with an effective diffusion coefficient D = const. * exp(-0.68/kT). The activation energy is consistent with a diffusion process that occurs preferentially through grain boundaries. The high value of the diffusion coefficient justifies the presence of Au at the Cr-Si interface after a low-temperature short-time heat treatment. At temperature > 370°C (the eutectic point of the Si-Au system) and after a longenough heat treatment, the Au is completely mixed with Si

Growth kinetics of NiSi on (100) and (111) silicon

The interaction of Ni film deposited on Si has been studied. Growth kinetics of Nisi on (111) and (100) silicon single crystals are reported. Activation energies for NiSi are found to be 1.23 eV for (100) and 1.83 eV for (111)

On the growth kinetics and structure of the NiSi compound on silicon single crystals

The growth kinetics of NiSi has been evaluated by depositing a Ni film on and Si substrates. X-ray diffraction and MeV 4He+ backscattering have been used to identify the compounds formed and to measure their thicknesses. Carbon and oxygen impurities have been detected with Auger electron spectrometry with Ar sputtering. During thermal annealing Ni~Si is formed first, while NiSi appears only after the total exhaustion of the Ni film. It has been found that, on both Si substrates, the thickness of NiSi increases with the square root of time. Different growth rates have been observed for the two different Si orientations. The activation energy in the (300-370) °C temperature range is 1.83 eV for NiSi grown on and 1.23 eV for NiSi on Si. The two competing mechanisms of Ni diffusion through NiSi by grain boundary and by substitutional processes are correlated with the different microcrystalline structure of the NiSi silicide layers grown on different Si oriented substrates

Radiation emission associated with switching in crystalline boron

Infrared radiation associated with switching in Boron single crystals was detected and analyzed. The time correlation between switching and radiation events, spectral distribution of the radiation, and its intensity as a function of current and temperature are reported. All the observed features suggest that recombination processes are the origin of this phenomenon and give information on the postswitching conduction mechanism of Boron

Switching effect in beta-rhombohedral boron

Switching effects were studied in high-resistivity undoped beta-rhombohedral Boron at 77-400 K using electrical and electrooptical measurements. The data collected must be interpreted with different models describing the origin of the switching action, i.e. double injection at low temperatures ( 77-250 K) and thermal instability at higher temperaures (250-400 K). A description of the main physical events givingrise to switching for double injection in the investigated sample is given. Emission of ir radiation in the postswitching regime due to hole-electron recombination is also reported

Determination of trapping centers in beta-rhombohedral boron

Trapping levels and their parameters were studied in high-resistivity, undoped beta-rhombohedral Boron. The study was performed by means of transient photoconductivity, space-charge-limited currents, and thermally stimulated currents. The analysis of the results given by the three methods provides a completely self-consistent model of the trap distribution in energy. A number of specimens were investigated and selfconsistentresults for all samples were found by the three methods. Hole trapping centers deep in the gap are present. In some samples, an exponential distribution starting from 0.36 eV above the valence band was found, together with a discrete shallow (0.02-0.05 eV) level. In other samples, a discrete level at 0.23 eV from the valence band is obsd. Energy traps for electrons are found at ~0.25 eV below the conduction band. The exptl. results are discussed with respect to the transport properties of Boron