Rapid interface parameterization using a single MOS conductance curve

Abstract

Figures are presented for finding interface trap density D it capture probability c p , and interfacial broadening σ s , from a single curve of small-signal MOS interface trap conductance G it / ω vs either band bending ν s , or frequency f[ ω = 2 πf]. Almost no computation is necessary. An additional figure allows the depletion layer capacitance to be determined if the oxide capacitance and the measured capacitance at the maximum value of G it / ω are known. The extension to G it / ω vs ν s , curves is a convenience. Parameters throughout the bandgap can be obtained from measurements at fewer frequencies than are needed for construction of accurate G it / ω vs f curves. Economy also results because data usually are obtained by sweeping gate bias at selected frequencies. Construction of G it / ω vs ν s curves from the data is simpler than G it / ω vs f, particularly if ν s is measured directly. The information needed from the G it / ω curve is the maximum value of G it / ω and the width of the peak at an arbitrary fraction of its maximum value, fw. In addition, for capture probability only, the frequency and band bending at the peak maximum are needed, as well as the bulk doping. The method assumes validity of the Gaussian approximation to broadening of the conductance peak. Comparison of the parameters obtained for several choices of fw allows a check of this assumption, which usually is valid for MOS devices.