Well-width dependence of intersubband absorption in InGaAs/InAlAs multiquantum wells

The well-width dependence of intersubband absorption in InGaAs/InAlAs multiquantum wells grown by molecular beam epitaxy is investigated. The energies of the absorption peaks decrease from 300 to 100 meV with an increasing well width from 35 to 200 Å. This well-width dependence of the peak energy is in good agreement with theoretical calculations. For a wide quantum well, two sharp absorption peaks were observed, including the transitions from the second to the third subbands.