Virtual cathode apparition in Pt/a-Si:H Schottky barrier under illumination and applied voltage

The behavior of illuminated Pt/a-Si:H Schottky barrier has been studied by numerical calculations. The electric field, the electrons and holes currents, the charge space and the recombination rate where calculated as function of the position. The photocurrent, when the front of the barrier is illuminated by different wavelengths under lower reverse applied voltage, tends towards saturation. By comparing the number of collected carriers to the incoming photons, we remark that the collection of photogenerated carriers is partial for long wavelengths (λ ≥ 600 nm), in this case the collection efficiency is determined by the recombination in the bulk, and total when the short wavelengths (λ < 600 nm) are used and the recombination in the front layer seems to be an important carrier loss mechanism. This is mainly the consequence of the virtual cathode apparition that behaves against the carrier collection. This cathode moves to back contact and tends to disappear with increasing the reverse bias voltage

Ab-initio investigation on the electronic and thermoelectric properties of new half-Heusler compounds KBiX (X = Ba and Sr)

International audienceElectronic structures and thermoelectric (TE) properties of KBiBa and KBiSr half-Heusler compounds are investigated by using the combined framework of first-principles and semi-classical Boltzmann transport theory. Elastic and phonon properties calculations reveal that these compounds are mechanically and dynamically stable. Band structures calculations, using the Tran and Blaha modified Becke-Johnson potential including spin-orbit coupling, show that KBiBa and KBiSr compounds are semiconductors with an indirect bandgap of 0.88 and 0.95 eV respectively. Performing calculations on lattice thermal conductivity, deformation potential, effective mass of charge carriers and their relaxation times allow us to deduce the dependence of the figure of merit ZT on doping concentration and temperature. At 1200 K, KBiBa and KBiSr compounds exhibit a ZT peak value of 2.68 and 1.56 at optimizedn-doping values of 2.2 × 1019and 1.7 × 1019 cm-3, respectively. Considering high ZT values, KBiBa and KBiSr are considered to be ideal TE candidates at high temperature

First-principles calculations of the electronic structure and Mossbauer parameters of Sb-doped SnO(2)

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Electronic structures and magnetic behavior of Al-, Si-, P- and Cl-doped ZnS

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