Packaged structure optimization for enhanced light extraction efficiency and reduced thermal resistance of ultraviolet B LEDs.
Opt Express
; 32(7): 12438-12448, 2024 Mar 25.
Article
en En
| MEDLINE
| ID: mdl-38571066
ABSTRACT
Ultraviolet B light-emitting diodes (UVB LEDs) hold promise in medical and agricultural applications. The commonly used sapphire substrate for their epitaxy growth possesses a high refractive index and excellent UV light absorption characteristics. However, this high refractive index can induce total internal reflection (TIR) within the substrate, leading to decreased Light Extraction Efficiency (LEE) due to light absorption within the material. In this study, UVB LED chips were detached from the sub-mount substrate and directly affixed onto an aluminum nitride (AlN) substrate with superior heat dissipation using a eutectic process. This was undertaken to diminish packaged thermal resistance (PTR). Simultaneously, optimization of the UVB LED packaging structure was employed to alleviate LEE losses caused by the TIR phenomenon, with the overarching goal of enhancin external quantum efficiency (EQE). The final experimental findings suggest that optimal LEE is achieved with packaging dimensions, including a length (ELL) of 2 mm, a width (ELW) of 1.62 mm, and a height (ELH) of 0.52 mm. At an input current of 200â
mA, the output power reaches 50â
mW, resulting in an EQE of 6.3%. Furthermore, the packaged thermal resistance from the chip to the substrate surface can be reduced to 4.615â
K/W.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Idioma:
En
Revista:
Opt Express
Asunto de la revista:
OFTALMOLOGIA
Año:
2024
Tipo del documento:
Article
Pais de publicación:
Estados Unidos