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Effect of hydrogen (H2) treatment during the GaN barrier growth on the electroluminescence performance of green InGaN/GaN single-quantum-well light-emitting diodes (LEDs) grown on Si substrates is experimentally investigated. We prepare two LED samples with different carrier gas compositions during the growth of GaN barrier. In the H2free LED, the GaN barrier is grown in full nitrogen (N2) atmosphere. For the other H2treated LED, a mixture of N2and H2was used as the carrier gas. It is observed that V-shaped pits decrease in size after H2treatment by means of the scanning electron microscope. Due to the fact that the p–n junction interface would be closer to the p-GaN as a result of smaller V-shaped pits, the tunneling barrier for holes to inject into the InGaN quantum well would become thicker after H2treatment. Hence, the external quantum efficiency of the H2treated LED is lower compared to the H2free LED. However, LEDs would exhibit a better leakage behavior after H2treatment during the GaN barrier growth because of more effective blocking of the threading dislocations as a result of the H2etching at V-shaped pits. [ABSTRACT FROM AUTHOR]

A blue emission originated from InGaN/GaN superlattice (SL) interlayer is observed in the yellow LEDs with V-pits embedded in the quantum wells (QWs), revealing that sufficient holes have penetrated through the QWs into SLs far away from the p-type layer. In the V-pits embedded LEDs, hole transport has two paths: via the flat c-plane region or via the sidewalls of V-pits. It is proved that the holes in SLs are injected from the sidewalls of V-pits, and the transportation process is significantly affected by working temperature, current density, and the size of V-pits. Four motion possibilities are discussed when the holes flow via the sidewalls. All these may contribute to a better understanding of hole transport and device design. [ABSTRACT FROM AUTHOR]

InGaN-based green light-emitting diodes (LEDs) with different growth temperatures of superlattice grown on Si (111) substrates are investigated by temperature-dependent electroluminescence between 100 K and 350 K. It is observed that with the decrease of the growth temperature of the superlattice from 895°C to 855°C, the forward voltage decreases, especially at low temperature. We presume that this is due to the existence of the larger average size of V-shaped pits, which is determined by secondary ion mass spectrometer measurements. Meanwhile, the sample with higher growth temperature of superlattice shows a severer efficiency droop at cryogenic temperatures (about 100 K–150 K). Electron overflow into p-GaN is considered to be the cause of such phenomena, which is relevant to the poorer hole injection into multiple quantum wells and the more reduced effective active volume in the active region. [ABSTRACT FROM AUTHOR]