Degradation scenario B (Barrier Sample Clauses

Degradation scenario B (Barrier trap generation) As a second possible degradation scenario, acceptor traps were placed in the AlGaN barrier layer. With reference to Figure 1, NRA ≠ 0, NSA = NBA= 0, LDAM = LGD. This degradation scenario will be referred to as degradation scenario B. Obtained results are qualitatively the same as for scenario A. Gate-lag amplification is reproduced by simulations and can be explained as the consequence of the capture and emission of gate-injected electrons. Similarly, the reverse IG is predicted to drop at increasing NRA, as a consequence of gate potential-barrier broadening and attendant gate electron injection reduction. The DC ID drop observed at high VGS after stress can, however, not be matched by simulations. This happens because gate electron injection is small at high VGS and almost all barrier traps are therefore neutral. From a quantitative point of view, however, the barrier trap density per unit area (NRA) must be increased by about one order of magnitude with respect to the NSA values assumed under the degradation scenario A, to obtain the same current-collapse magnitude and reverse IG drop. In this respect, simulations point out that only the acceptor traps closer to the gate contact are in fact reached by gate-injected electrons and become negatively charged under reverse VGS.