Cyclotron Resonance of Localized Electrons on a Si Surface

Cyclotron resonance of electrons in an inversion layer on a Si (100) surface is studied in the regime of low electron densities ($n_s<{10}^{12}$ electrons/${\mathrm{cm}}^2$). A distinct and sample-dependent shift of the resonance to lower magnetic field is observed as $n_s$ is decreased and electron localization is expected to occur. We give a simple interpretation of the effect in terms of electronic states bound in a harmonic-oscillator potential.