Light-emitting diodes with surface gallium nitride p–n homojunction structure formed by selective area regrowth

In this study, the blue light-emitting diode (LED) structures based on gallium nitride (GaN) were presented. Each structure possessed a surface GaN p–n junction, which was formed through selective area regrowth on an InGaN/GaN multiple quantum well (MQW) structure and served as the carrier injector. The LEDs that showed efficient hole injection and current spreading were configured to form a p-type GaN layer between the MQW and regrown n-type GaN top layer. These LEDs exhibited higher luminous efficiency and lower operation voltage than the LEDs with regrown p-type GaN top layers. The LEDs with n-type GaN top layers emitted single-peak spectra at approximately 450 nm under a forward bias. The UV peak at 365 nm (i.e., the GaN band-edge emission) was absent because the regrown surface GaN p–n junctions behaved as carrier injectors rather than photon injectors. In other words, the single-peak blue emission was not generated by the optical pumping of UV light emitted from the surface p–n GaN homojunction.