Quantum-Confined Stark Effect Analysis of GeSn/SiGeSn Quantum Wells for Mid-Infrared Si-Based Electroabsorption Devices Based on Many-Body Theory

Quantum-confined Stark effect (QCSE) of group IV Ge(Sn)/SiGe(Sn) quantum wells (QWs) on Si substrate is analyzed by microscopic many-body theory for mid-infrared (mid-IR) Si-based electroabsorption devices. To show the validity of the theory, QCSE of Ge/SiGe QW is investigated and very good agreement between theory and reported measured results is obtained. Next, the QCSE of GeSn/SiGeSn QWs is analyzed and the QW design for electroabsorption modulators to obtain large extinction ratio in mid-IR region is presented. It is shown that compressive and tensile strained well and barrier layers is preferable to obtain large extinction ratio due to its large conduction band offset.