公开(公告)号：US20230103072A1

公开(公告)日：2023-03-30

申请号：US17747351

申请日：2022-05-18

申请人： UNIVERSITY OF SOUTH CAROLINA

发明人： RICHARD FLOYD ,  ASIF KHAN ,  MIKHAIL GAEVSKI ,  MVS CHANDRASHEKHAR ,  GREGORY SIMIN

IPC分类号： H01L33/62 ,  H01L33/32 ,  H01L27/15 ,  H01L33/64 ,  H01L33/00

摘要： A 1.8-times improved light extraction efficiency (LEE) is reported under DC test conditions for truncated cone AlGaN DUV micropixel LEDs when the pixel size was reduced from 90 to 5 µm. This is shown to be a direct consequence of the absorption of the TM-polarized photons travelling in a direction parallel to the device epitaxial layers. Presently disclosed cathodoluminescence measurements show the lateral absorption length for 275 nm DUV photons to be 15 µm, which is ~1000 times shorter than that for waveguiding in the A0.65Ga0.35N cladding layers. Results show the re-absorption of this laterally travelling emission by the multiple quantum wells and the p-contact GaN layer to be a key factor limiting the LEE. Hence, for DUV emitters, scaling down to sub-20 µm device dimensions is critical for maximizing LEE. Presently disclosed sub-20 µm AIGaN-based LEDs do not show pronounced edge recombination effects. The peak light output power was further increased for all the devices after the addition of a semi -reflective Al2O3/Al heat spreader despite the reduction in sidewall reflectivity.