University of California Santa Barbara (UCSB) in the USA has been using silicon carbide (SiC) substrates to grow aluminium gallium nitride (AlGaN) structures aimed at 278nm deep ultraviolet (UV-C, 100-280nm wavelength) light-emitting diodes (LEDs) [Burhan K. SaifAddin et al, ACS Photonics, published online 27 January 2020]. The researchers used surface roughening of thin-film flip-chip devices to boost light-extraction efficiency (LEE) by a factor of 3 over smooth-faced LEDs.