Electron localization and noise in silicon carbide inversion layers

Abstract

In silicon carbide inversion layers, a high interface disorder results in the existence of numerous localized states and in a thermally activated transport, even at room temperature. The minimum value of the conductivity intercept σ_int is close to 0.1e ² /h, and the activation energy E_A has a strong dependence on gate voltage. Low‐frequency noise measurements indicate that the noise power spectral density of the conductivity could be due to mobility fluctuations rather than fluctuations in the number of carriers via trapping‐detrapping into the insulator. The system follows the Hooge relation, and the number of electrons which is relevant for application of the formula is exactly equal to the number of carriers excited above the mobility edge. Also, the noise measurements confirm that the change in σ _int with electron concentration N_S results mainly from a change in the Fermi level with temperature, and not from a change in the pre‐exponential factor of the conductivity with N_s .