Tunability of intersubband absorption from 4.5 to 5.3 μm in a GaN/Al0.2Ga0.8N superlattices grown by metalorganic chemical vapor deposition

Intersubband (ISB) absorption at wavelengths as long as 5.3 μm is realized in GaN/Al0.2Ga0.8N superlattices grown by metalorganic chemical vapor deposition. By employing low aluminum content Al0.2Ga0.8N barriers and varying the well width from 2.6 to 5.1 nm, ISB absorption has been tuned from 4.5 to 5.3 μm. Theoretical ISB absorption and interband emission models are developed and compared to the experimental results. The effects of band offsets and the piezoelectric fields on these superlattices are investigated.