Abstract: The invention relates to a solar cell containing a semiconductor (1) with an intermediate band (2) that is half filled with electrons, located between two layers of ordinary n type (3) and p type (4) semiconductors. When lighted, electron-hole pairs are formed either by a photon that absorbs the necessary energy (5) or by two photons (6,7) that absorb less energy which pump an electron from the valence band to the intermediate band (8) and from the latter to the conductance band (9). An electrical current is generated that exits on the p side and returns via the n side. The n and p layers also prevent the intermediate band from contacting the outer metal connections, which would have resulted in a short-circuit. Said cell converts solar energy into electricity in a more efficient manner than conventional cells and contributes to improvement of the photovoltaic devices.

Abstract: An electric field having a strength of approximately 15 V/nm is applied between a tungsten tip and a metallic substrate. Concomitantly, the tip is heated to a temperature less than the bulk melting temperature of the tungsten tip. Atoms at the surface of the tip move and form a pyramidal protrusion of nanometer scale on the tip. Topmost atoms on the protrusion are charged and form a coherent beam useful for writing atomic scale structures on the substrate.