Ammonia 1 GaInN GaN 1 GaN cap layers 1 Gallium nitride 1 Gas molecules 1 Gas-sensors 1 Human breath 1 Hydrogen sulfide 1 Hydrogen sulfide sensor 1 III-V semiconductors 1 Medical professionals 1 Metal-organic vapour phase epitaxy 1 Organometallics 1 Photoluminescence signals 1 Quantum-confined Stark effect 1 Quantum-wells 1 Semiconductor alloys 1 Semiconductor quantum wells 1 Sulfur determination 1 ammonia 1 gas sensors 1 hydrogen sulfide 1