High-Brightness Wafer-Bonded Indium-Tin Oxide/Light-Emitting Diode/Mirror/Si

[[abstract]]Indium-tin oxide (ITO) used as the window layer and current-spreading layer for wafer-bonded AlGaInP/mirror/Si light-emitting diodes (MS LEDs) has been reported. The ITO films prepared by sputtering have low resistivity (2.1×10-4 Ω-cm) and high transmittance (>90% in the visible region). The MS LEDs incorporating the ITO layer and In/ITO provide higher light output than ITO-free MS LEDs. They also exhibit a linear increase of a uniform distributed light output without radiation saturation as the injection current increases. Moreover, the MS LED, ITO/MS LED and ITO/In/MS LEDs provide 2.8, 3.0 and 3.4 times improvement in external power efficiency, respectively, as compared with the absorbing-substrate LED fabricated from the same AlGaInP LED wafer. Due to the inserted In layer that reduces the contact resistance between ITO and the GaAs contact layer without causing obvious absorption of the emitting light, the ITO/In/MS LEDs can achieve the highest power conversion efficiency among the LEDs studied