Impact of the applied electric field on the optical absorption coefficient in Ge/Si1-xGex step quantum well (SQW)

In the present work, we theoretically investigated the impact of quantum well width and electric field on the intersubband optical absorption coefficient (OACs) of Ge/Si1-xGex step quantum well (SQW). The calculation is made within the framework of effective mass theory (EMT) at room temperature (RT). The discrete energy levels and their related wave functions are computed by solving the Schrödinger Equation by using the finite difference method (FDM). The intersuband optical absorption coefficient is discussed and evaluated based on the Compact Density Matrix (CDE) approach. The results reveal that the self-energy and the intersubband transition (ISBT) are drastically affected by the applied electric field (EF) and well width. The peak position of OACs experiences a red or blue shift following the direction of EF (forward and reverse polarization). This kind of structure allows an opportunity for tuning and manipulating the intersubband optical absorption coefficient which is of great importance for the design and the realization of high-frequency optoelectronic and photonic devices.