Properties of InGaN/AlInGaN/AlGaN quantum-well UV light-emitting diodes

摘要

Properties of InGaN/AlInGaN/AlGaN single- and multiple-quantum-well (MQW) light-emitting diodes grown by MOCVD on sapphire substrates are investigated over a wide temperature range from 12 to 298 K. The room-temperature (RT) UV emission band, observed in both single-quantum-well (SQW) and MQW samples, is at 3.307 eV (375 nm) and its full width at half maximum is ～82 meV. In addition to the UV band, a blue emission band at 2.96 eV (419 nm) is observed in SQW samples. The relative intensities of these UV and blue emission bands depend on the injection current. We attribute the blue emission to the carrier overflow over the quantum well (QW) and subsequent radiative recombination involving a Mg-related-level in p-GaN. In MQW LEDs, we observe an anomalous temperature-induced "blue jump" between 170-190 K, with the main emission peak switching from blue to UV. The blue band emission dominates below 170 K, and is practically absent at RT. Thus, we demonstrate a significant advantage in utilizing MQW structures that provide a more effective capture of injected carriers into the QWs.