Extremely broadband quantum-dot LEDs realized via rapid thermal annealing

Researchers at the University of Sheffield (Sheffield, England) and the Chinese Academy of Sciences (Beijing) have reported the first demonstration of ultrabroadband superluminescent light-emitting diodes (SLEDs) with a multiple quantum-dot (QD) layer structure. The V-groove QD-SLED structure, fabricated via a rapid thermal annealing process, is based on a typical p-i-n configuration, beginning with a silicon-doped (100) gallium arsenide (GaAs) substrate. Five layers of indium arsenide (InAs) QDs make up the active region, in between a 1 µm cladding layer of n-Al0.5Ga0.5As and another 1 µm cladding layer of p-Al0.5Ga 0.5As.

After a 750°C rapid thermal annealing process, the electroluminescent emission spectra of three QD-SLEDs injected with 1200 mA of current exhibits a 3 dB bandwidth spanning 146 nm, from 892 to 1038 nm. The blueshifting of the emission peak to 984 nm is attributed mainly to state filling and higher-energy QD- and quantum-well-like states. The obtained continuous-wave output power at room temperature was as high as 15 mW. Broadband superluminescent sources have potential in numerous applications such as spectrum-sliced wavelength-division-multiplexing systems, fiber gyroscopes, and optical-coherence tomography. Contact Ziyang Zhang at [email protected].