Stress voltages on time-dependent breakdown characteristics of GaN MIS-HEMTs during negative gate bias stress (with VGS < 0, VD = VS = 0) and off-state stress (VG < VTh, VDS > 0, VS = 0) are investigated. For...Stress voltages on time-dependent breakdown characteristics of GaN MIS-HEMTs during negative gate bias stress (with VGS < 0, VD = VS = 0) and off-state stress (VG < VTh, VDS > 0, VS = 0) are investigated. For negative bias stress, the breakdown time distribution (β) decreases with the increasing negative gate voltage, while β is larger for higher drain voltage at off-state stress. Two humps in the time-dependent gate leakage occurred under both breakdown conditions, which can be ascribed to the dielectric breakdown triggered earlier and followed by the GaN layer breakdown. Combining the electric distribution from simulation and long-term monitoring of electric parameter, the peak electric fields under the gate edges at source and drain sides are confirmed as the main formation locations for per-location paths during negative gate voltage stress and off-state stress, respectively.展开更多
Sulfur-containing dynamic polymers had attracted significant attention due to their unique chemical structures with high reversibility.Utilizating sulfur, an inexpensive industrial waste product, to synthesize dynamic...Sulfur-containing dynamic polymers had attracted significant attention due to their unique chemical structures with high reversibility.Utilizating sulfur, an inexpensive industrial waste product, to synthesize dynamic polysulfide polymers through reverse vulcanization has been a notable approach. However, this method required high temperatures and resulted in the release of unpleasant oders. In this study, we presented a robust method for the preparation of sulfur-rich polymers with dynamic polysulfide bonds from elemental sulfur and inexpensive epoxide monomers via a one-pot strategy at the mild room temperature. Different types of polysulfide molecules and polymers were synthesized by reacting various epoxide compounds with sulfur, along with the investigation of their structures and dynamic behaviors. It was noteworthy that the obatined polymers prepared from m-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl)aniline and elemental sulfur exhibit multiple dynamic behaviors, including polysulfide metathesis and polysulfide-thiol exchange, enabling their rapid stress relaxation, self-healing, reprocessing and degradable properties of the cross-linked polymer. More importantly, the hydroxyl groups at the side chains from epoxide ring opening exhibited potential transesterification. This work provided a facile strategy for designing dynamic sulfur-rich polymers via a mild synthesis route.展开更多
基金Project supported by the National Key Research and Development Program,China(Grant No.2017YFB0402800)the Key Research and Development Program of Guangdong Province,China(Grant Nos.2019B010128002 and 2020B010173001)+4 种基金the National Natural Science Foundation of China(Grant No.U1601210)the Natural Science Foundation of Guangdong Province,China(Grant No.2015A030312011)the Open Project of Key Laboratory of Microelectronic Devices and Integrated Technology(Grant No.202006)the Science and Technology Plan of Guangdong Province,China(Grant No.2017B010112002)the China Postdoctoral Science Foundation(Grant No.2019M663233).
文摘Stress voltages on time-dependent breakdown characteristics of GaN MIS-HEMTs during negative gate bias stress (with VGS < 0, VD = VS = 0) and off-state stress (VG < VTh, VDS > 0, VS = 0) are investigated. For negative bias stress, the breakdown time distribution (β) decreases with the increasing negative gate voltage, while β is larger for higher drain voltage at off-state stress. Two humps in the time-dependent gate leakage occurred under both breakdown conditions, which can be ascribed to the dielectric breakdown triggered earlier and followed by the GaN layer breakdown. Combining the electric distribution from simulation and long-term monitoring of electric parameter, the peak electric fields under the gate edges at source and drain sides are confirmed as the main formation locations for per-location paths during negative gate voltage stress and off-state stress, respectively.
基金financially supported by the State Key R&D Program of China (No. 2019YFA0706801)the National Natural Science Foundation of China (No. 52173079)the Fundamental Research Funds for the Central Universities (Nos. xtr052023001 and xzy022024024)。
文摘Sulfur-containing dynamic polymers had attracted significant attention due to their unique chemical structures with high reversibility.Utilizating sulfur, an inexpensive industrial waste product, to synthesize dynamic polysulfide polymers through reverse vulcanization has been a notable approach. However, this method required high temperatures and resulted in the release of unpleasant oders. In this study, we presented a robust method for the preparation of sulfur-rich polymers with dynamic polysulfide bonds from elemental sulfur and inexpensive epoxide monomers via a one-pot strategy at the mild room temperature. Different types of polysulfide molecules and polymers were synthesized by reacting various epoxide compounds with sulfur, along with the investigation of their structures and dynamic behaviors. It was noteworthy that the obatined polymers prepared from m-(2,3-epoxypropoxy)-N,N-bis(2,3-epoxypropyl)aniline and elemental sulfur exhibit multiple dynamic behaviors, including polysulfide metathesis and polysulfide-thiol exchange, enabling their rapid stress relaxation, self-healing, reprocessing and degradable properties of the cross-linked polymer. More importantly, the hydroxyl groups at the side chains from epoxide ring opening exhibited potential transesterification. This work provided a facile strategy for designing dynamic sulfur-rich polymers via a mild synthesis route.