Determination of Si-SiO2 interface trap density by 1/f noise measurements

The concentration of silicon-silicon dioxide interface traps with energies down to within 20 meV of the majority-carrier band edge was determined using 1/f noise measurements. p-type diffused resistors of four-probe geometry were fabricated in a metal-oxide-silicon structure. Flicker noise measurements were performed on these devices at cryogenic temperatures of 20 to 280 K. Using A. L. McWhorter´s (1957) 1/f noise model and the calculated position of the Fermi level with respect to the valence band edge at each temperature, the density of interface traps was calculated at energy levels corresponding to the position of the Fermi level at that temperature. This technique is proposed as an alternate method to measure the oxide trap and slow interface-state densities with energies close to the band edges