MBE-grown 232-270 nm Deep-UV LEDs using Monolayer thin Binary GaN/AlN   quantum heterostructures
  Electrically injected deep ultra-violet (UV) emission is obtained using monolayer (ML) thin GaN/AlN quantum structures as active regions. The emission wavelength is tuned by controlling the thickness of ultrathin GaN layers with monolayer precision using plasma assisted molecular beam epitaxy (PAMBE). Single peaked emission spectra is achieved with narrow full width at half maximum (FWHM) for three different light emitting diodes (LEDs) operating at 232 nm, 246 nm and 270 nm. 232 nm (5.34 eV) is the shortest EL emission wavelength reported so far using GaN as the light emitting material and employing polarization-induced doping. 
SM Islam, Kevin Lee, Jai Verma, Vladimir Protasenko, Sergei Rouvimov,   Shyam Bharadwaj, Huili Xing, and Debdeep Jena
cond-mat.mtrl-sci physics.optics