High Bandwidth Freestanding Semipolar (11–22) InGaN/GaN Light-Emitting Diodes

• Main Authors: Zhiheng Quan, Duc V. Dinh, Silvino Presa, Brendan Roycroft, Ann Foley, Mahbub Akhter, Donagh O'Mahony, Pleun P. Maaskant, Marian Caliebe, Ferdinand Scholz, Peter J. Parbrook, Brian Corbett
• Format: Article
• Language: English
• Published: IEEE 2016-01-01
• Series: IEEE Photonics Journal
• Subjects: Light-emitting diodes (LEDs); optoelectronic materials; semipolar gallium nitride (GaN); laser lift-off (LLO); metal organic vapor phase epitaxy (MOVPE)
• Online Access: https://ieeexplore.ieee.org/document/7553585/
• ISSN: 1943-0655

Freestanding semipolar (11-22) indium gallium nitride (InGaN) multiple-quantum-well light-emitting diodes (LEDs) emitting at 445 nm have been realized by the use of laser lift-off (LLO) of the LEDs from a 50-μm-thick GaN layer grown on a patterned (10-12) r-plane sapphire substrate (PSS). The GaN grooves originating from the growth on PSS were removed by chemical mechanical polishing. The 300 μm × 300 μm LEDs showed a turn-on voltage of 3.6 V and an output power through the smooth substrate of 0.87 mW at 20 mA. The electroluminescence spectrum of LEDs before and after LLO showed a stronger emission intensity along the [11-23]InGaN/GaN direction. The polarization anisotropy is independent of the GaN grooves, with a measured value of 0.14. The bandwidth of the LEDs is in excess of 150 MHz at 20 mA, and back-to-back transmission of 300 Mbps is demonstrated, making these devices suitable for visible light communication (VLC) applications.