Category Technology/Electronics

Schematic of the epitaxial growth procedure of ZnSe/GaAs heterostructure growth using either light-start or dark-start growth procedures. (a) Prior to ZnSe epilayer growth, the GaAs epilayer was grown in a dedicated III-V MBE chamber and was covered with an amorphous arsenic film prior to transferring it to a dedicated II-VI chamber. (b) The amorphous arsenic film was then thermally desorbed and the interface growth was initiated with a Zn pre-treatment under either a light-start or dark-start condition. During light-start sample growth, UV light was directed onto the growth surface from the beginning of Zn pre-treatment until the end of the ZnSe growth (f–h). During dark-start sample growth, UV light was directed onto the growth surface only during ZnSe epilayer growth (c–e).

1. The selective solar absorber (SSA) developed by the researchers appears black, and thus absorptive, under sunlight (as shown on the photograph on the left). However, for thermal radiation, it behaves like a non-emissive metal mirror (reflecting the dark blue sky, as shown on the thermograph on the right), and prevents the absorbed solar energy from being radiated away and lost.
—Figure courtesy of Jyotirmoy Mandal and Yuan Yang/Columbia Engineering
2. The researchers make their SSAs using a dip-and-dry technique which is considerably simpler than common manufacturing methods for SSAs.
—Photo courtesy of Jyotirmoy Mandal and Yuan Yang/Columbia Engineering

Metal oxides are promising candidates for cheap and stable photoelectrodes for solar water splitting, producing hydrogen with sunlight. Unfortunately, metal oxides are not highly efficient in this job. A known remedy is a treatment with heat and hydrogen. An international collaboration has now discovered why this treatment works so well, paving the way to more efficient and cheap devices for solar hydrogen production. Credit: HZB

The perovskite material changes size when exposed to light. Reproduced with permission from reference 1.© 2017 WILEY‐VCH Verlag GmbH & Co.