Abstract
Quantum cascade lasers (QCLs) are long-wavelength and high-power semiconductor lasers employing carrier recycling in an active region. Since this laser utilizes an intersubband transition in quantum well structures, fundamental properties such as the laser emission wavelength are dependent on the design of structures. However ultimate laser performance depends not only on designing the structures but also on material properties. Here we have discussed semiconductor material systems suitable for the operation of QCLs. The material properties, which have an influence on laser characteristics, are presented and compared with the laser performance of state-of-art QCLs composed by the different kinds of materials. Finally we have described our recent results using In As/AISb which has material properties advantageous for the operation of QCLs.
