MBE Growth of (Ga,In)As/Al(As,Sb) MQWs for Intersubband Transition Wavelenghts < 3.5 Micron

Intersubband transitions in InP-based (Ga,In)As/(Al,In)As MQWs cover the wavelength range beyond 3.5 micron. Application of enhanced conduction band edge discontinuity allows for a reduced intersubband transition wavelength. This can be accomplished by replacing (Al,In)As by Al(As,Sb) barriers that can be grown lattice-matched to InP. (Ga,In)As/Al(As,Sb) MQWs were deposited by MBE and characterised using a combination of x-ray diffraction, photoluminescence and IR absorption measurements. Influence of well thickness and doping behaviour were systematically investigated. By
comparison with simplified theoretical calculations, the electronic band structure (interband and intersubband system) was deduced. Based on the corresponding results, the potential of (Ga,In)As/Al(As,Sb) MQWs for implementation in quantum cascade lasers will be discussed.