Enhanced coherent THz emission from [100] GaAs in the presence of a magnetic field

Summary form only given.A THz field may be generated at the surface of a semiconductor by surface field photoconduction (SFP). In this process, photogenerated carriers are accelerated by the built-in surface field within the depletion region and their coherent motion results in the cooperative emission of THz radiation. A significant enhancement in the THz power generated by SFP has been previously observed when a magnetic field is applied to InAs. In the present experiment, we investigate the effects of magnetic fields up to 8 T on the THz emission from a bulk [100] n-type MBE-grown GaAs sample (carrier density n=1*10/sup 15/(cm/sup -/3)). The sample was illuminated at an angle of 45/spl deg/ by a 70-fs pulse centred at 760 nm. The magnetic field was applied in the plane of incidence parallel to the reflected THz beam. The emitted THz radiation was measured both by an incoherent bolometer detection scheme and coherent free-space electro-optic sampling.