Silicon Heterojunction Solar Cells with Epitaxial Buffer Layer on Textured Substrates

In the present work we report recent results for silicon heterojunction solar cells deposited by conventional Plasma Enhanced Chemical Vapor Deposition (PECVD) technique on textured Czochralski (CZ) silicon wafers. A new texturing technique was developed using a wet anisotropic chemical etching with a tetramethyl-ammonium hydroxide (TMAH) solution. An increase of the device photogenerated current, with maximum short circuit current of more then 36 mA/cm2 was attained. A study of the first stages of device layer growth is presented with relation to plasma ignition in PECVD systems. An original passivation technique of the amorphous/crystalline interface defects was implemented for textured wafers. Using this scheme a reproducible efficiency in excess of 16% was obtained on CZ textured wafers

“Astonishing successes” and “bitter disappointment”: The specific heat of hydrogen in quantum theory

The specific heat of hydrogen gas at low temperatures was first measured in 1912 by Arnold Eucken in Walther Nernst’s laboratory in Berlin, and provided one of the earliest experimental supports for the new quantum theory. Even earlier, Nernst had developed a quantum theory of rotating diatomic gas molecules that figured in the discussions at the first Solvay conference in late 1911. Between 1913 and 1925, Albert Einstein, Paul Ehrenfest, Max Planck, Fritz Reiche, and Erwin Schrödinger, among many others, attempted theoretical descriptions of the rotational specific heat of hydrogen, with only limited success. Quantum theory also was central to the study of molecular spectra, where initially it was more successful. Moreover, the two problems interacted in sometimes surprising ways. Not until 1927, following Werner Heisenberg’s discovery of the behavior of indistinguishable particles in modern quantum mechanics, did American theorist David Dennison find a successful theory of the specific heat of hydrogen