Effect of intense terahertz laser and magnetic fields on the binding energy and the transition energy of shallow impurity in a bulk semiconductor

The influences of intense terahertz laser and magnetic fields on shallow-donor states in GaAs bulk semiconductors in the Faraday geometry are studied theoretically in the framework of the effective-mass approximation. The interaction between the laser field and the semiconductor is treated nonperturbatively by solving analytically the time-dependent Schrödinger equation in which the two external fields are included exactly. In the nonresonant region, we have found that the binding and transition energies decrease with increasing laser-field intensity or decreasing laser-field frequency, and the binding energy increases with magnetic field. For relatively low radiation levels, the transition energy first slowly decreases with increasing magnetic field, but after a critical value, it rapidly increases with increasing magnetic field. However, it slowly decreases with magnetic field when the laser-field intensity is strong enough. Furthermore, in the vicinity of the resonant regime, the oscillatory behaviours of the binding and transition energies with laser-field frequency and magnetic field are observed. These results obtained indicate the possibility of manipulating the shallow impurity states in semiconductor by changing the intense laser-field frequency and intensity and the magnetic field, which gives a new degree of freedom in semiconductor device application.