For different donor distribution types we theoretically investigate the intersubband transitions of single Si delta-doped GaAs structure as dependent on the applied electric held. The diffusion of donor impurities is taken into account in two different models: a triangular distribution and a non-uniform distribution. The electronic properties such as the effective delta-potential, the subband energies and the eigen-envelope wavefunctions have been calculated by solving the Schrodinger and Poisson equations self-consistently. Abrupt changes of the subband energy difference and the absorption peak are realized whenever the applied electric field reaches a certain value.. These critical electric field values change dependent on the donor distribution model. The intersubband absorption spectrum shows that redshifts appear up to the critical electric field value for the (1-2) and (1-3) intersubband transitions. This spectrum also shows that blueshifts can occur when the electric fields are higher than certain values. These changing intersubband absorption peaks can be used in various infrared optical device applications.