Growth properties and electrochemical characterization of InGaN photoanodes with different In concentrations

The generation of hydrogen via the photochemical electrolysis of water by employing a semiconductor photoelectrode is a promising approach for a renewable energy source. In this work, InGaN layers grown by metal‐organic vapour phase epitaxy (MOVPE). Different In concentrations were achieved by variation of the growth temperature between 800 °C and 720 °C. The properties of the layers were investigated by high‐resolution X‐ray diffraction (HRXRD), Rutherford backscattering spec‐trometry (RBS) and atomic force microscopy (AFM). The maximum In concentration at the GaN/InGaN interface is 11%. A further increase towards the surface at lower growth temperatures is achieved by relaxation. This causes a change in the growth mode from 2D to 3D and an overall decrease of crystal quality. Additionally, two Si‐doped InGaN layers were grown with In contents of 7% and 25% to investigate its influence on properties of a photoanode. The photoanodes were electrochemically examined via chronoamperometry in a three‐electrode configuration. It is shown that at low voltages EWE between working electrode and reference electrode, the photocurrent of the sample with 7% In is higher, whereas for voltages above 0.8 V, it is vice versa. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)