Cyclotron Resonance Line-Broadening due to Ionized Impurity Scattering in Germanium

The broadening of cyclotron resonance line due to ionized impurity scattering has been measured in a germanium crystal containing both antimony and copper of about 10 14 cm -3 in a 50 Gc-band experiment at 11°K. Use of a heavily compensated specimen together with an attenuated carrier-producing illumination has made possible to observe the broadening effect which has not been in the experiments ever performed. By analyzing the increment of half-width, the relaxation time for ionized impurity scattering has been evaluated, which is in approximate agreement with the value from the Conwell-Weisskopf formula. The result may be reasonably accepted, since, in the present experimental condition, the mean cyclotron radius is comparable with or larger than the magnitude of the force range of the scattering potential.