Two-dimensional magneto-plasmons in Si∕SiGe quantum wells

Abstract

Abstract. X-band microwave spectroscopy in a commercial EPR spectrometer at 1.5 K on modulation doped Si quantum well structures exhibits a relatively broad signal due to the coupled cyclotron-plasmon resonance, allowing to estimate both the carrier density and the electron mobility. After illumination above band gap, some of our heavily Sb-doped samples show a persistent splitting of this signal. Evaluation of the mobility yields a substantial increase of the mobility in the Si channel. Our results demonstrate that a major part of the scattering in the channel results from long range fluctuations of the Coulomb potential due to ionized donors in the doping channel. We attribute the substantial reduction in momentum scattering to screening of potential fluctuations within the doping layer by the additional carriers there.