Subthreshold Slope of Long-channel, Accumulation-mode P-channel Soi Mosfets

An analytical model for the subthreshold slope of the accumulation-mode p-channeI SOI MOSFET is developed. The exact solution of the equations reveals that the subthreshold swing is slightly larger (by a few percent) than that of enhancement (inversion-mode) fully depleted SOI devices. In most cases, however, the classical subthreshold slope expression developed for inversion-mode fully depleted SOI MOSFET can be used as a good approximation for accumulation-mode devices, which means that the subthreshoId swing tends to the ideal value of S-0 = kT/q 1n(10) mV/dec if the buried oxide is sufficiently thick and if the interface trap density is sufficiently low.