Cyclotron Resonance in Space Charge Layers on Si

Cyclotron resonance of electrons bound in quantized states in space charge layers on a (100) surface of Si has been observed. We have seen the electron resonance in both inversion and accumulation layers. For the case of inversion the cyclotron mass m_c^* is found to differ substantially from the bulk value 0.1905 m₀ and to vary with the surface density of electrons (Q_s). We find m_c^*=0.230 m₀ for Q_s≈0.2 ×10¹² electrons/cm², which decreases to m_c^*=0.230 m₀ for Q_s ≈2.0×10¹² electrons/cm². The relaxation time from cyclotron resonance exhibits a maximum near Q_s≈0.8×10¹² electrons/cm² for the inversion layer. In recent work^* we have discovered in addition to the fundamental resonance an approximately subharmonic sequence of peaks, which we attribute to cyclotron resonance perturbed by charged trap states at the Si–SiO₂ interface. We also find cyclotron resonance of electrons in an accumulation layer on n-type (100) Si with mass m_c^* close to the bulk value.