Sharp intersubband absorption spectra in AlGaN/GaN multiple quantum wells

Summary form only given.Intersubband transition (ISBT) in AlGaN-GaN multiple quantum wells (MQWs) is very important to fabricate optical modulators and/or cascade lasers in the 1.5 /spl mu/m telecommunication wavelength. in this work, we observed the sharp ISBT spectra for high-quality AlGaN/GaN MQWs and investigated systematically the number of QWs dependence on spectral linewidth. When the number of QW layers was reduced from 30 to 5, the linewidth decrease from 57 meV to 32 meV. From this systematic experiment, the ISBT linewidth for the single QW layer was evaluated to be 20 meV. This value shows good agreement with the theoretical energy broadening induced by one monolayer fluctuation of QW thickness, indicating that very smooth heterointerfaces have been successfully obtained.