Microdisk-Type Multicolor Semipolar Nitride-Based Light-Emitting Diodes

Recently, III-nitride semiconductors have gained immense attention for application in high-performance optoelectronic devices. However, in the device fabrication process, it is essential to develop a wet-etching process for conventional polar nitride-based devices to reduce the dry-etching damage. In this study, semipolar microdisk (MD)-type light-emitting diodes (LEDs) are fabricated using only a wet-etching process. The wet-etching rate of the n-type GaN film is the highest, followed by those of the undoped and p-type GaN films. The n- and p-type GaN films exhibit upward and downward surface-band-bending heights, respectively, because of which they can easily attract and repel OH– to form Ga2O3. In addition, the fully wet-etched MD-LED shows high light extraction efficiency from the etched nanofacets because of the increase in the escape cone angle with low etching damage. The smaller diameters of the MD-LEDs result in shorter emission wavelengths, allowing multicolor emission ranging from the violet (∼420 nm) to amber (∼620 nm) wavelengths to be achieved on a single LED wafer. Thus, monolithic multicolor emissions and increased light output power are achieved by fabricating parallel-connected MD-LED arrays using only a wet-etching process.