Metal-organic chemical vapor deposition growth of InGaN/GaN high power green light emitting diode: Effects of InGaN well protection and electron reservoir layer

We investigated the effects of the well protection layer (WPL) and electron reservoir layer (ERL) on the emission properties of InGaN/GaN green multiple quantum wells (MQWs). In order to increase their emission wavelength by preventing the volatile InGaN well, a thin GaN WPL was coated subsequently on each well layer at the same temperature before ramping-up the temperature to grow the GaN barrier. It was found that the WPL directly influenced the indium content and optical properties of the MQW. The indium content was in fact increased, as was evident from the x-ray diffraction and photoluminescence experiments. Then, to explore the possibility of enhancing the quantum efficiency by increasing the electron capture rate, a superlattice ERL composed of ten pairs of InGaN/GaN was embedded between the MQW and n-GaN. The electroluminescence intensity of the green light emitting diode with the ERL was up to three times higher than that of the diode without the ERL. These results imply that the carrier capture by the MQW is significantly improved by the additional superlattice ERL, which consequently leads to the enhancement of the quantum efficiency.