Far-infrared measurements of cyclotron resonance and impurity transitions in bulk n-GaAs in pulsed magnetic fields

The photoconductive response of n-GaAs has been measured under laser radiation in the wavelength range 71 to 513 /spl mu/m at temperatures as low as 400 mK and at magnetic fields as high as 42 T. A rich variety of spectral features are observed: cyclotron resonance, transitions associated with D/sup -/, and transitions to stable and metastable hydrogenic states. The use of a pulsed magnet has extended the magnetic field range over which data is available by a factor of three.