Improvement of green InGaN-based LEDs efficiency using a novel quantum well structure

The green light emitting diodes(LEDs)have lower quantum efficiency than LEDs with other emission wavelengths in the visible spectrum.In this research,a novel quantum well structure was designed to improve the electroluminescence(EL)of green InGaN-based LEDs.Compared with the conventional quantum well structure,the novel structure LED gained 2.14times light out power(LOP)at 20-mA current injection,narrower FWHM and lower blue-shift at different current injection conditions.     

Visualizing light-to-electricity conversion process in InGaN/GaN multi-quantum wells with a p-n junction

Absorption and carrier transport behavior plays an important role in the light-to-electricity conversion process, which is difficult to characterize. Here we develop a method to visualize such a conversion process in the InGaN/GaN multiquantum wells embedded in a p-n junction. Under non-resonant absorption conditions, a photocurrent was generated and the photoluminescence intensity decayed by more than 70% when the p-n junction out-circuit was switched from open to short. However, when the excitation photon energy decreased to the resonant absorption edge, the photocurrent dropped drastically and the photoluminescence under open and short circuit conditions showed similar intensity. These results indicate that the escaping of the photo-generated carriers from the quantum wells is closely related to the excitation photon energy.