Magnetic field enhanced THz generation from semiconductor surfaces
The generation of THz radiation from semiconductor surfaces utilizing the surface depletion/enrichment field is a well established technique and has been examined in detail. THz radiation emitted from semiconductor surfaces can be considerably enhanced applying an external magnetic field. We have performed a systematic study of the power enhancement caused by an external magnetic field for five different semiconductor materials (InSb, InAs, InP, GaAs, GaSb). In particular, we distinguish between the fraction of THz radiation, which was generated by the magnetic field and the surface depletion/enrichment field, respectively. This was possible using time resolved measurements of the THz waveform.
Using a simple Lorentz model for the acceleration of the carriers with a linear approximation, we have found that the power enhancement caused by the magnetic field is proportional to the square of the applied field for magnetic fields of up to 1 T. The scaling factor for the power enhancement is inversely proportional to the effective electron mass:
