Atomically sharp 318 nm Gd:AlGaN ultraviolet light emitting diodes on Si with low threshold voltage

Self-assembled Al_xGa_1–xN polarization-induced nanowire light emitting diodes (PINLEDs) with Gd-doped AlN active regions are prepared by plasma-assisted molecular beam epitaxy on Si substrates. Atomically sharp electroluminescence (EL) from Gd intra-f-shell electronic transitions at 313 nm and 318 nm is observed under forward biases above 5 V. The intensity of the Gd 4f EL scales linearly with current density and increases at lower temperature. The low field excitation of Gd 4f EL in PINLEDs is contrasted with high field excitation in metal/Gd:AlN/polarization-induced n-AlGaN devices; PINLED devices offer over a three fold enhancement in 4f EL intensity at a given device bias.