Design of InxGa1−xAs1−yNy∕AlAs quantum cascade structures for 3.4μm intersubband emission

Abstract

We report the design of an active region of In x Ga 1−x As 1−y N y / AlAs quantum cascade laser structure emitting in the near infrared wavelength range based on an eight-band k • p model. The In x Ga 1−x As 1−y N y / AlAs heterostructure system is of significant interest for the development of short wavelength quantum cascade lasers due to its large conduction band discontinuity ͑ϳ1.5 eV͒ and compatibility with the mature GaAs fabrication process. A detailed analysis of the intersubband transition energy within the conduction band as a function of layer thickness, composition, electric field, and temperature has been carried out. Finally, an optimized combination of In 0.2 Ga 0.8 As 0.97 N 0.03 / AlAs three-coupled-well structure has been obtained. Under an applied field of 100 kV/ cm and at room temperature, a shortest wavelength of 3.4 m has been achieved by making use of this system without introducing an upper lasing level beyond the X minima of the AlAs barrier.