Reliability of AlGaN-based deep UV LEDs on sapphire

Maxim Shatalov; Zheng Gong; Mikhail Gaevski; Shuai Wu; Wenhong Sun; Vinod Adivarahan; M. Asif Khan

doi:10.1117/12.647204

22 February 2006 Reliability of AlGaN-based deep UV LEDs on sapphire

Maxim Shatalov, Zheng Gong, Mikhail Gaevski, Shuai Wu, Wenhong Sun, Vinod Adivarahan, M. Asif Khan

Proceedings Volume 6134, Light-Emitting Diodes: Research, Manufacturing, and Applications X; 61340P (2006) https://doi.org/10.1117/12.647204
Event: Integrated Optoelectronic Devices 2006, 2006, San Jose, California, United States

Abstract

Deep UV LEDs emitting at on 280 nm with powers as high as 1 mW at 20 mA have been reported recently. These devices have mesa size of 100 μm x 100 μm to avoid current crowding due to the high Al-composition of the AlxGa_1-xN buffer layers. Small mesa size results in pump current density of 200 A/cm² for a device current of 20 mA. Small area of p-contact also leads to higher operating voltage and higher thermal impedance for the flip-chip packaged device. These factors limit the device lifetime for 50 % power reduction to only a few hundred hours. From temperature and bias dependent power degradation measurements we found the output power to decay with two characteristic time constants indicating two degradation mechanisms. The faster time constant is bias dependent and temperature independent. The slower time constant varies exponentially with junction temperature having the activation energy of 0.27 eV at 200 A/cm² pump current density. For the devices with high thermal impedance this degradation mechanism controls the long term power degradation. To increase the device area for better reliability we used the interconnected micro-pixel device design with 10x10 array of 22 μm in diameter pixels. This design allowed for the four-fold increase of the junction area and thereby led to improved reliability performance with the operation life-time for 50 % power reduction of about 1000 hours. In this paper we will present the details of the reliability measurements and use the experimental results to determine possible degradation mechanisms.

Citation Download Citation

Maxim Shatalov, Zheng Gong, Mikhail Gaevski, Shuai Wu, Wenhong Sun, Vinod Adivarahan, and M. Asif Khan "Reliability of AlGaN-based deep UV LEDs on sapphire", Proc. SPIE 6134, Light-Emitting Diodes: Research, Manufacturing, and Applications X, 61340P (22 February 2006); https://doi.org/10.1117/12.647204

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available