Intersubband linear and nonlinear optical response of the delta-doped SiGe quantum well

•We calculate linear and non-linear intersubband optic properties of QWs.•Energy structure of delta-doped inside well QWs was calculated self-consistently.•We allowed for the impurity binding energy change.•Edge-doped well gives an additional peak in absorption with small nonlinearity.•The effects studied can be used to engineer tunable THz optical devices.

The degree of ionization, controlled by external fields, of delta-doped layers inside the quantum wells can affect their energy structure, therefore delta-doped QWs can be used to engineer different kinds of tunable THz optical devices on intersubband transitions. Here it is calculated and analyzed the linear and nonlinear (Kerr-type) optical response, including absorption coefficient and refractive index change of 20 nm-wide Si0.8Ge0.2/Si/Si0.8Ge0.2 QW structures n-delta-doped either at the center or at the edge of the well under different temperatures. The conduction subband energy structure was found self-consistently, including the calculation of the impurity binding energy. Our results show that the degree of ionization of the impurity layer as well as the heterostructure symmetry has a strong influence on optical properties of the structures in THz region.