Far-infrared determination of cyclotron and plasma-shifted cyclotron resonances in thin MBE-grown films of α-Sn

Far-infrared cyclotron resonance and plasma-shifted cyclotron resonance were observed in thin layers of alpha -Sn grown by molecular beam epitaxy on CdTe substrates, and were used to determine the effective mass m* of electrons at the Gamma point and to estimate the dielectric constant epsilon . In these experiments the plasma-shifted cyclotron resonance was observed for the first time at frequencies below the plasma edge, omega < omega _p. The data give m*=0.0333+or-0.0002, the matrix element E _p=24.0+or-0.5 and an estimate of epsilon approximately=23 for a sample with an electron concentration n approximately=3*10¹⁷ cm^-3, in good agreement with earlier results obtained on bulk samples.