Impact of Mobility Degradation and Supply Voltage on Negative-Bias Temperature Instability in Advanced p-Channel Metal–Oxide–Semiconductor Field-Effect Transistors

Abstract

Recently, the CoGeNT experiment has reported events in excess of expected background. We analyze dark matter scenarios which can potentially explain this signal. Under the standard case of spin independent scattering with equal couplings to protons and neutrons, we find significant tensions with existing constraints. Consistency with these limits is possible if a large fraction of the putative signal events is coming from an additional source of experimental background. In this case, dark matter recoils cannot be said to explain the excess, but are consistent with it. We also investigate modifications to dark matter scattering that can evade the null experiments. In particular, we explore generalized spin independent couplings to protons and neutrons, spin dependent couplings, momentum dependent scattering, and inelastic interactions. We find that some of these generalizations can explain most of the CoGeNT events without violation of other constraints. Generalized couplings with some momentum dependence allow further consistency with the DAMA modulation signal, realizing a scenario where both CoGeNT and DAMA signals are coming from dark matter. A model with dark matter interacting and annihilating into a new light boson can realize most of the scenarios considered.

Abnormal degradation of high-voltage p-type MOSFET with n+ polycrystalline silicon gate during AC stress

“…2) Whenever the gate node is biased negatively, the threshold voltage of HV pMOSFET shifts and the performance of transistor is degraded. In prior reports, [3][4][5][6] researchers focused on the pMOSFETs with thin gate oxides and the degradation of the pMOSFET is entirely due to negative bias temperature instability (NBTI). However, an electric field (E-field) of HV pMOSFET in a level shifter is higher than 6 MV=cm, and it is necessary to consider the effect of the Fowler-Nordheim (FN) tunneling.…”

“…One is the early and gradual degradation by NBTI, and which is well-known from prior works. [3][4][5][6] The other is the abnormal and drastic degradation which occurs after the gradual degradation by NBTI. This abnormal degradation is suppressed effectively by changing the gate material from n+ poly-Si to p+ poly-Si in spite of higher oxide E-field, and it has been never reported previously.…”

“…The early degradation occurs before ∼3000 s, and this degradation agrees with prior NBTI reports. [3][4][5][6] When the gate electrode is biased negatively, the threshold voltage is shifted by the mechanism of NBTI, and the degradation slope has powerlaw dependency. However, the degradation is accelerated drastically after ∼3000 s. According to Fig.…”