Degradation of the Channel Transport Parameters Sample Clauses

Degradation of the Channel Transport Parameters. As already concluded from the analysis of Figure 2.21, trap generation alone is unable to explain the features of gm degradation induced by off-state stress. By analogy with degradation effects observed in Si MOSFETs [65], it was speculated that channel-mobility decrease could play a major role in off-state stress. To explore this hypothesis, we analyzed the impact on the gm curve of a decrease in both low-field electron mobility (μn) and electron velocity saturation (vsat) in the intrinsic channel. Figure 2.23 shows simulated gm vs VGS curves at a VDS of 7 V for pre-stress conditions and different values of μn and vsat percentage reduction. As can be noted, the gm curve decreases almost rigidly at increasing μn and vsat degradation. In agreement with conclusions drawn from Figure 2.21, acceptor traps were placed in a narrow region of the drain-access region (LDAM=LGD/16≈84 nm) within the cap, the barrier, and the buffer (same trap volume densities and trap energies as for degradation scenario E), this preventing gm from dropping predominantly at high VGS. pre-stress Δvsat = Δμn =10% vsat μn 30% 50%