Characteristics of drain-modulated generation current in n-type metal-oxide-semiconductor field-effect transistor

Drain-modulated generation current I_DMG induced by interface traps in an n-type metal-oxide-semiconductor field-effect transistor (nMOSFET) is investigated. The formation of I_DMG ascribes to the change of the Si surface potential φ_s. This change makes the channel suffer transformation from the inversion state, depletion I state to depletion II state. The simulation result agrees with the experiment in the inversion and depletion I states. In the depletion II state, the theoretical curve goes into saturation, while the experimental curve drops quickly as V_D increases. The reason for this unconformity is that the drain-to-gate voltage V_DG lessens φ_s around the drain corner and controls the falling edge of the I_DMG curve. The experiments of gate-modulated generation and recombination currents are also applied to verify the reasonability of the mechanism. Based on this mechanism, a theoretical model of the I_DMG falling edge is set up in which I_DMG has an exponential attenuation relation with V_DG. Finally, the critical fitting coefficient t of the experimental curves is extracted. It is found that t=80 mV=3kT/q. This result fully shows the accuracy of the above mechanism.