A Study Of The Influence Of Indium-tin-oxide To GaN-based Light-emitting Diodes

In order to improve the light efficiency of the conventional GaN-based light-emitting diodes(LEDs)，the indium tin oxide (ITO) film is introduced as the current spreading layer and the lighttransmitting layer on the P-GaN surface. In this thesis, the transparent and conductive IndiumTin-Oxide (ITO) thin films were evaporated on glasses and annealed in furnace. The effects ofthe film thicknesses and annealing conditions on the photoelectrical properties of ITO films werestudied by measuring the sheet resistance (Rs) and transmittance of ITO films. Then,205μm×508μm blue light-emitting diodes with different ITO thicknesses and annealing conditions werefabricated. Forward voltage, light intensity distribution, light output power and luminous flux at20mA injection current were measured to investigate the characteristics and the performance ofITO films on GaN based LEDs.The results showed that with thickness of250nm, annealing temperature at400℃, N2flowat10L/min and annealing time at30min, the ITO film could obtain the highest quality. Thesheet resistance (Rs) was12/□and transmittance was above95%. LEDs made in theoptimized conditions had forward voltage of3.18V, output power of26.11mW and the luminousflux of7.81lm at20mA injection current.