The carrier recombination ABC model is a powerful tool to understand the performance of Light-Emitting Diodes (LEDs) such as Light Extraction Efficiency (LEE), Internal Quantum Efficiency (IQE), and lifetime. Starting from the ABC model we demonstrate that the optical-output-power junction-temperature dependence can be used to obtain an LED’s LEE and IQE. Using this analysis to a high power Deep Ultraviolet (DUV) LED and a state-of-the-art blue LED we obtain LEE values of 16% and 80% for the DUV and blue LEDs, respectively. This points LEE to be the main factor for efficiency improvement of DUV LEDs. Also, if IQE (not LEE) is responsible for the optical power decay, an LED lifetime model based on the ABC carrier recombination can be established to predict LED’s lifetime, and the model shows that the LED lifetime is mainly determined by the initial defect density and the defect generation interest rate. We present room temperature lifetime measurement data up to 3,000 hours for some 267 nm DUV LEDs, and the lifetime to maintain 70% of the initial optical power (L70) according to the lifetime model can be extrapolated to be of 20,000 to 120,000 hours. In view of the data presented in this paper, high-efficiency, long-lifetime DUV LEDs can be realized if the light extraction efficiency, initial defect density and uniform current spreading can be optimized.
We report a transparent 269 nm deep ultraviolet (UV) light-emitting diode (LED) with a thin Mg-doped AlN p-type ohmic contact layer. At 20 mA direct current, the forward voltage is 6.2 V and the optical output power is 11.8 mW, translating into wall-plug-efficiency (WPE) and external quantum efficiency (EQE) equal to 9.5% and 12.8%, respectively. The device maintains 70% of its original optical output power for more than 1000 hours (L70≥1000 hrs) at a current density (J) of 88.9 A/cm2. Experimental data support that this device will have a significantly increased L70 for J ≤ 30 A/cm2. We also demonstrate that for deep UV LEDs the EQE vs current-density (EQE-J) curve can be well fitted by the standard carrier recombination model (ABC model), and internal quantum efficiency (IQE) and light-extraction efficiency (LEE) can thus be extracted. Furthermore, we propose a method for quick assessment of LED’s lifetime, through fitting of EQE-J curves before and after short-term reliability test.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
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.