Enhanced deep ultraviolet emission from Si-doped Al_xGa_1-xN/AlN MQWs

Undoped and Si-doped AlGaN/AlN multiple quantum wells (MQWs) were grown on AlN/Sapphire templates by metalorganic phase vapor epitaxy. High-resolution x-ray diffraction measurements showed the high interface quality of the MQWs little affected by Si-doping. Room-temperature (RT) cathodoluminescence measurements demonstrated a significant enhancement of the RT deep ultraviolet emission at about 240 nm from the AlGaN/AlN MQWs by Si doping. The mechanism of the improved emission efficiency was that the Si-doping partially screens the internal electric field and thus leads to the increase of the overlap between electron and hole wavefunctions. Further theoretical simulation also supports the above results.