Nitride-based heterostructures grown by MOCVD for near- and mid-infrared intersubband transitions

Intersubband (ISB) optical absorption in different nitride‐based heterostructures grown by metal‐organic chemical vapour deposition (MOCVD) is reported. The role of indium in AlInN/GaN multi‐quantum wells (MQWs) is investigated. At high concentration (15%) AlInN is quasi lattice‐matched to GaN and no cracks appear in the structure. At very low indium concentration (∼2%) the material quality is improved without decreasing the ISB transition wavelength with respect to the case of indium‐free structures. Different mechanisms of strain relaxation in pure and 2% indium‐doped AlN/GaN MQW structures are also investigated. ISB transition wavelengths of 2 μm for AlN/GaN MQWs, and 3 μm for AlInN/GaN MQWs with 15% of In are achieve