Enhanced performance of 275-nm AlGaN-based deep-ultraviolet LEDs via internal-roughed sapphire and SiO₂-antireflection film

Abstract

The internal-roughed sapphire in a 275-nm AlGaN-based deep-ultraviolet (DUV) LED is fabricated using a laser stealth dicing technique to improve the high-angle extraction. Furthermore, the low-angle extraction is enhanced by depositing a SiO2-antireflection film on the internal-roughed sapphire surface. Compared with conventional DUV LEDs with a light output power (LOP) of 33.05 mW at 350 mA, the LOP of DUV LEDs with internal-roughed sapphire and SiO2-antireflection film increases by 20.85% to 39.94 mW. In addition, combined with finite-difference time-domain simulations, the effect of internal-roughed sapphire on the transmission and light extraction efficiency (LEE) of the DUV LEDs is revealed. The combination of the internal-roughed sapphire substrate and SiO2-antireflection film improves the LEEs of transverse electric (TE) and transverse magnetic (TM) polarized light by 1.6% and 108%, respectively. These results offer the potential for large-scale, low-cost industrial production of high-efficiency DUV LEDs.

Recent Progress in III‐Nitride Tunnel Junction Light‐Emitting Diodes

“…Due to p-type doping difficulty and high Mg ionization energy (0.14 eV for GaN and 0.63 eV for AlN), and high p-type work function, p-AlGaN layer suffers from poor conductivity and high contact resistance. [95][96][97][98][99][100][101][102][103][104] Thus, p-GaN layer is typically deposited on top of UV LEDs to form an ohmic contact. [105][106][107][108] However, the absorption of UV light by p-GaN leads to strong optical loss.…”