Spotlight on etching: (11-22) semipolar GaN plane light-emitting diodes (LEDs) are demonstrated using a wet-etching process. A trigonal prism cell structure with a (0001) c plane and nnn{10-10} m planes is formed after KOH wet etching, and leads to a better ohmic contact and enhanced light extraction. LEDs fabricated by wet etching show excellent output performance 1.89 times higher than that of the reference LEDs.

We report a dramatic increase in the light extraction efficiency of GaN-based blue light-emitting diodes (LEDs) by ZnO nanorod arrays on a planar indium tin oxide (ITO) transparent electrode. ZnO nanorods were grown into aqueous solution at the low temperature of 90 °C. With 20 mA current injection, the light output efficiency of the LED with ZnO nanorod arrays on ITO was increased by about 57% with no increase in a forward voltage over the conventional LEDs with planar ITO. The increased light extraction by the ZnO nanorod arrays is due to the formation of sidewalls and a rough surface, resulting in a multiple photon scattering at the LED surface.

We report on low-resistance Ti (50 nm)/Au (80 nm) contacts to amorphous gallium indium zinc oxides (a-GIZO). The specific contact resistances obtained using the transmission line method were as low as 2.85×10−5 Ω cm2 when annealed at 500 °C for 1 min in N2 ambient. This could be attributed to the combined effects of structural relaxation of a-GIZO films at elevated temperatures, causing drastic increases in both electron concentration and Hall mobility, and to interfacial reactions between Ti/Au and a-GIZO layers producing oxygen vacancies near the surface.

Improvements of external quantum efficiency of InGaN-based blue light-emitting diodes at high current density using GaN substrates