Strain effects in GaN/AlN multi-quantum-well structures for infrared optoelectronics
We report on the effect of Al mole fraction in AlGaN substrates on the strain state and on the intersubband (ISB) absorption properties of GaN/AlN multi-quantum-well (MQW) structures. The MQWs present the same strain state in all the samples irrespective of the Al concentration in the substrate. As a consequence, the ISB transition energy was found to be independent of Al content in the substrate. In situ characterization during growth reveals a progressive relaxation in the GaN quantum wells and a combination of elastic and plastic relaxation in AlN barriers.
strain gan intersubband quantum well mbe