In this study, n-type Al-doped MgxZn1-xO (AMZO) films were deposited onto p-Al0.08Ga0.92N by using radiofrequency
magnetron sputtering followed by annealing at 800°C in nitrogen ambient for 60 s. The film was highly
transparent and had transmittances exceeding 95% in the visible region and a sharp absorption edge visible in the
ultraviolet region. A high leakage current was obtained in the current-voltage (I-V) characteristics of the GMZO/AlGaN
n-p junction diode. The AMZO/AlGaN photodetector based on the AMZO film exhibited a dark current of 1.56 μA at
Vbias = -3V. The peak responsivity of the photodetector was approximately 200 nm and a cutoff wavelength was
observed at approximately 250 nm.
GaN-based flip-chip light emitting diodes (FC-LEDs) with embedded air voids grown on a selective-area Arimplanted AlN/sapphire (AIAS) substrate was demonstrated in this study. The proposed FC LED with an embedded light scattering layer can destroy the light interference and thereby increase the LEE of GaN-based flip-chip LEDs. The epitaxial layers grown on Ar-implanted regions exhibited lower growth rates compared with those grown on implantation-free regions. Accordingly, air voids formed over the implanted regions after merging laterally grown GaN facet fronts. The light-output power of LEDs grown on AIAS was greater than that of LEDs grown on implantation free sapphire substrates. At an injection current of 700 mA, the output power of LEDs grown on AIAS was enhanced by 20% compared with those of LEDs without embedded air voids. The increase in output power was mainly attributed to the scattering of light around the air voids, which increased the probability of photons escaping from the LEDs. This study on FC LEDs with embedded light-scattering layer highlights the potential application of these LEDs as an alternative to conventional patterned sapphire substrates for improving the LEE of GaN/sapphire-based LEDs. Based on ray tracing simulation, if the height and the width of bottom of gaps were increased to 3 μm, the Lop could be enhanced over 60%.