Correlation between indium content in monolithic InGaN/GaN multi quantum well structures on photoelectrochemical activity for water splitting

In this study, monolithic InGaN/GaN multi-quantum well structures (MQWs) were grown on sapphire substrate at various growth temperatures by metal organic chemical vapor deposition (MOCVD) method and were used for the hydrogen evolution through photoelectrochemical water splitting. The periodicity and indium concentration of monolithic InGaN/GaN MQWs, surface morphology and optical bandgap of the device structure were studied using high resolution x-ray diffraction, atomic force microscope and photoluminescence analysis respectively. The roughness and bandgap values of InGaN/GaN MQWs were found to decrease with increasing indium content. Furthermore, the influence of indium content on the photoelectrochemical hydrogen evaluation via water splitting activity of monolithic InGaN/GaN MQWs under simulated solar radiation of AM 1.5G (100 mW/cm2) were explored. The photocurrent density increased with increase of indium content due to the changes in charge transfer resistance, flat band potential and increase of donor density. The enhanced photoelectrochemical activity demonstrated by this monolithic InGaN/GaN MQWs reveals that it is suitable candidate for the light energy harvesting applications.