Absorption and emission studies of the quantum-limit cyclotron resonance linewidth in n-InSb

A systematic study of quantum-limit cyclotron resonance linewidth in several n-InSb samples has been carried out as a function of total ionized impurity concentration, free-carrier concentration, temperature, and magnetic field in a temperature range where ionized-impurity scattering is expected to be dominant. Both farinfrared laser transmission measurements and hot-electron emission measurements were performed. The wavelength and magnetic field range investigated were 70 to 500 μm and 23 to 3 kG, respectively. The linewidth is found to be proportional to the square root of the total ionized impurity concentration, and a minimum in the linewidth as a function of magnetic field is observed in all samples. Within experimental error the magnitude of the linewidth and the magnetic field position of the minimum linewidth are independent of free-carrier concentration indicating that free-carrier screening of the ionized impurities does not play a role. These results are discussed and interpreted in light of existing theories.