Plasma Induced Deep Ultraviolet Emissions From ZnO-based Films

Deep ultraviolet (DUV) light source with wavelength shorter than300nm playsan important role in food sterilization, water purification, clinical diagnostics and soon. However, the currently widely used DUV light sources are xenon lamps, mercurylamps, etc. It is accepted that the above DUV light sources suffer from short lifetime,poor stability and portability. DUV light sources fabricated from wide bandgapsemiconductors offer the advantages of long lifetime, good stability and portability,thus much attention has been attracted in the past decades.MgZnO-based materials have large bandgap that can cover the DUV spectrumrange. Also they have the advantages of large exciton binding energy,environment-friendly, rich in raw materials, etc. Because of the above characters,MgZnO has been considered an ideal candidate for DUV light sources. To realizeefficient DUV light emission, p-n junctions are usually needed. Nevertheless, thep-type doping of such a wide bandgap is a huge challenge. Under such circumstance,plasma has been employed as the excitation source of the MgZnO films, and the mainresults obtained are as follows:Cubic rocksalt structured Mg0.54Zn0.46O flms have been prepared, and the flmsshow a wide bandgap of5.4eV. Obvious emission at around276nm has beendetected when the flms are placed in the ambient of plasma, and the output power ofthe plasma induced DUV emission can reach around56μW, which is the highestvalue ever reported for ZnO-based DUV light-emitters. The deep ultraviolet emission is believed to come from the Mg0.54Zn0.46O flms excited by the kinetic radicals of theplasma.