The effect of a transversal electric field on the impurity binding energy and the energy differences between the space-quantized subbands of center delta-doped SiGe/Si quantum well structure is studied numerically with a self-consistent method. The result is explained in terms of the concurrent effects of impurity ionization and the applied field. The predicted phenomenon can be used to tune the energy distances and, accordingly, the working frequencies of possible optical devices. © 2020 IEEE.