Tunability of intersubband transition wavelength in the atmospheric window in AlGaN/GaN multi-quantum wells grown on different AlGaN templates by metalorganic chemical vapor deposition

The properties of intersubband transition in AlGaN/GaN multi-quantum wells (MQWs) grown on different AlGaN templates by metalorganic chemical vapor deposition are investigated. The strain states of GaN wells are studied by Raman spectra and reciprocal space mappings, which shows that the GaN wells are compressively strained and the compressive strain is increased when the Al mole composition is varied from 0 to 0.3. The Fourier transform infrared spectrometer results show that the intersubband transition wavelength in the AlGaN/GaN MQWs can be tuned from 5.14 μm to 4.65 μm when the Al mole composition of the AlGaN template is increased. The results can be attributed to the quantum confined Stark effect.