Investigation of the Mechanism of Terahertz Radiation from InAs under Magnetic Fields

The magnetic field dependence of terahertz radiation from InAs excited by femtosecond laser pulses has been measured with the time-domain spectroscopy up to 10 T. The magnetic field dependence of n-InAs shows a radiation power minimum around 5 T whereas p-InAs does not show such a minimum. Additionally, it is found that the polarity of the amplitude of terahertz radiation is reversed at 5 T for n-InAs. This polarity reversal is attributed to a crossover of the radiation mechanism from the photo-Dember effect to magnetoplasma oscillations with increasing magnetic field.