Homoepitaxially grown GaN-based light-emitting diodes with peak emission at 405 nm

Near-ultraviolet InGaN/GaN multiple-quantum-well light-emitting diodes (LEDs) grown homoepitaxially on a free standing GaN substrate exhibited improved micro structural, electrical and optical properties compared to similar devices grown on sapphire. In contrast to strong tunneling behaviors in the LEDs on sapphire, thermally activated currents were observed at both forward and reverse biases in the LEDs on GaN. At low injection currents, the quantum efficiency of the LEDs on GaN was much higher, suggesting reduced nonradative recombination centers. At high driving currents, the homoepitaxial LEDs greatly outperformed the devices on sapphire as a result of improved material quality, heat dissipation and current spreading. These results show the promise of homoepitaxially grown GaN-based LEDs for solid-state lighting applications. (C) 2004 Elsevier B.V. All rights reserved.