In this letter, monolithic red, green, and blue (RGB) micro light-emitting diodes (LEDs) were fabricated using gallium nitride based blue micro LEDs and quantum dots (QDs). Red and green QDs were sprayed onto individual region surrounded by patterned black matrix photoresist on the blue micro LEDs to form color conversion layers. Owing to its light-blocking capability, the patterned black matrix photoresist improved the contrast ratio of the micro LEDs from 11 to 22. To enhance the color conversion efficiency and the light output intensity, a hybrid Bragg reflector (HBR) was deposited on the bottom side of the monolithic RGB micro LEDs, thus reflecting the RGB light emitted to the substrate. To further improve the color purity of the red and green light, a distributed Bragg reflector (DBR) with high reflection for the blue light was deposited on the top side of the QDs/micro LEDs. The red and green light output intensities of the micro LEDs with HBR and DBR were enhanced by about 27%.

To modulate the cutoff wavelength of the metal-semiconductor-metal deep ultraviolet photodetectors (MSM DUV-PDs), the aluminum content of the aluminum oxide-alloyed gallium oxide (Ga2O3:Al2O3) absorption layers were deposited using radio frequency (RF) magnetron cosputter system with dual targets, in which the Ga2O3 target was sputtered with a RF power of 100 W and the Al2O3 target sputtered with various RF powers. The optical bandgap energy of the Ga2O3:Al2O3 films increased with an increase of the Al content deposited with a larger sputtered RF power of the Al2O3 target. In view of the suppression effect of the oxygen vacancy and the defect by the more Al-O bonds in the Ga2O3:Al2O3 absorption layer, the noise performances and the detectivity of the MSM DUV-PDs were improved. For depositing the Al atomic percentage of 5.9 % in the Ga2O3:Al2O3 absorption layer, the resulting MSM DUV-PDs revealed the cutoff wavelength of 230 nm, the noise equivalent power of 2.80 × 10−12 W, and the detectivity of 1.37 × 1011 cmHz0.5W−1. Furthermore, the dominant low frequency noise source was the flicker noise.