Impact Statement:Al-rich p-EBL in DUV LED possesses serious issues i.e. p-doping and hole injection. We propose a new paradigm to shift from the electron blocking in p-EBL to the electron...Show More
Abstract:
AlGaN-based deep UV (DUV) LEDs generally employ a p-type electron blocking layer (EBL) to suppress electron overflow. However, Al-rich III-nitride EBL can result in chall...Show MoreMetadata
Impact Statement:
Al-rich p-EBL in DUV LED possesses serious issues i.e. p-doping and hole injection. We propose a new paradigm to shift from the electron blocking in p-EBL to the electron containing in the active region by deliberately-designed quantum barrier grading, thereby making EBL-free DUV LED feasible. We believe the work is highly innovative and significant with a straightforward approach. It can inspire the community to look beyond p-EBL to address electron overflow and enhance hole injection.
Abstract:
AlGaN-based deep UV (DUV) LEDs generally employ a p-type electron blocking layer (EBL) to suppress electron overflow. However, Al-rich III-nitride EBL can result in challenging p-doping and large valence band barrier for hole injection as well as epitaxial complexity. As a result, wall plug efficiency (WPE) can be compromised. Our systematic studies of band diagram and carrier concentration reveal that carrier concentrations in the quantum well and electron overflow can be significantly impacted because of the slope variation of the quantum barrier (QB) conduction and valence bands, which in turn influence radiative recombination and optical output power. Remarkably, grading the Al composition from 0.60 to 0.70 for the 12-nm-thick AlGaN QB of the DUV LED without the EBL can lead to 13.5% higher output power and similar level of overflown electron concentration (∼1 × 1015/cm3) as opposed to the conventional DUV LED with the p-type EBL. This paradigm is significant for the pursuit of higher WPE or shorter emission wavelength for DUV LEDs and lasers, as it provides a new direction for addressing electron overflow and hole injection issues.
Published in: IEEE Photonics Journal ( Volume: 11, Issue: 2, April 2019)