Advances in intermixed quantum well devices

Quantum well composition intermixing is a thermal induced interdiffusion of the constituent atoms through the hetero-interface. The intermixed structures created by both impurity induced and impurity free or vacancy promoted processes have recently attracted high attention. The interdiffusion mechanism is no longer confined to a single phase diffusion for two constituent atoms, but it can now consist of two or multiple phases and/or multiple species, such as three cations interdiffusion and two pairs of cation-anion interdiffusion. A review on the impact of intermixing on device physics is presented with many interesting features. For instance, both compressive or tensile strain materials and both blue or red shifts in the bandgap can be achieved depending on the types of intermixing. The recent advancement in intermixing modified optical properties, such as absorption, refractive index as well as electro-optic effects are discussed. In addition, this paper places a strong emphasis on the device application of the intermixing technology. The advantage of being able to tune the material provides a way to improve the performance of photodetectors and modulators. Attractive distributed-feedback and vertical cavity laser dynamics have been shown due to some unique device physics of the quantum well intermixing. Several state-of-the-art results will be summarized with an emphasis on its future development and directions.