Effect of barrier thickness on the interface and optical properties of InGaN/GaN multiple quantum wells

We investigated the effect of barrier thickness on the interfacial and optical properties of the InGaN/GaN multiple quantum wells (MQWs) grown in a low-pressure metalorganic chemical vapor deposition system. The GaN barrier thickness in the InGaN/GaN MQWs was found to play a key role to determine the interfacial structural and optical characteristics of the MQWs. As the thickness of the GaN barrier layer was increased, the abruptness of the interface between InGaN and GaN layers deteriorated, probably due to the generation of defects induced by the strain accumulation in the MQWs. Accordingly, the intensity and the line-width of the photoluminescence taken from the MQWs were reduced and broadened, respectively with the increase of the GaN barrier thickness. The InGaN/GaN MQWs grown with an optimized barrier thickness showed an intense room-temperature photoluminescence at the wavelength of 479.5 nm with a very narrow full width at half maximum of 40.82 meV.