Polarization property of deep-ultraviolet light emission from C-plane AlN/GaN short-period superlattices

AlN/GaN short-period superlattices (SLs) is experimentally shown to have a different polarization property from AlGaN. As the GaN well thickness decreases from 2.5 to 0.9 monolayers, the emission wavelength decreases from 275.8 to 236.9 nm due to a quantum size effect. Because the quantized energy level for holes originates from the heavy hole band of GaN, the emission is polarized for electric field perpendicular to the c-axis (E⊥c). Consequently, the SLs show intense C-plane emission compared with AlGaN, whose emission is inherently polarized for electric field parallel to the c-axis (E||c). Using the SLs, we demonstrate a E⊥c-polarized deep-ultraviolet (UV) light-emitting diode (LED).