Functionalized GaN/GaInN heterostructures for hydrogen sulfide sensing

Near-surface GaN/GaInN quantum wells (QWs) were investigated as optical transducers for the detection of hydrogen sulfide. The heterostructure sensors were grown by metal organic vapor phase epitaxy and later covered by a thin layer of Au by electron beam evaporation. The QW photoluminescence (PL) is sensitive to changes in the sensor surface potential. By the adsorption of hydrogen sulfide (H2S) on the Au cover layer, downward near-surface band bending results in an increase of the quantum confined Stark effect in the GaInN QW producing a red shift in its luminescence. Unexpectedly, an increase in PL intensity is also observed. A concentration of 0.01 parts per million of H2S in nitrogen has been successfully detected. This phenomenon may be helpful to detect trace amounts of H2S present in the human breath for early detection of diseases. (C) 2019 The Japan Society of Applied Physics