We investigate the effects of NO annealing and forming gas （FG） annealing on the electrical properties of a SiO2/SiC interface by low-temperature conductance measurements. With nitrogen passivation, the density of i...We investigate the effects of NO annealing and forming gas （FG） annealing on the electrical properties of a SiO2/SiC interface by low-temperature conductance measurements. With nitrogen passivation, the density of interface states （DIT） is significantly reduced in the entire energy range, and the shift of flatband voltage, AVFB, is effectively suppressed to less than 0.4 V. However, very fast states are observed after NO annealing and the response frequencies are higher than 1 MHz at room temperature. After additional FG annealing, the DIT and AVFB are further reduced. The values of the DIT decrease to less than 1011 cm-2 eV- 1 for the energy range of Ec - ET 〉/0.4 eV. It is suggested that the fast states in shallow energy levels originated from the N atoms accumulating at the interface by NO annealing. Though FG annealing has a limited effect on these shallow traps, hydrogen can terminate the residual Si and C dangling bonds corresponding to traps at deep energy levels and improve the interface quality further. It is indicated that NO annealing in conjunction with FG annealing will be a better post-oxidation process method for high performance SiC MOSFETs.展开更多
The m-machine no-wait flowshop scheduling problem is addressed where setup times are treated as separate from processing times. The objective is to minimize total tardiness. Different dispatching rules have been inves...The m-machine no-wait flowshop scheduling problem is addressed where setup times are treated as separate from processing times. The objective is to minimize total tardiness. Different dispatching rules have been investigated and three were found to be superior. Two heuristics, a simulated annealing (SA) and a genetic algorithm (GA), have been proposed by using the best performing dispatching rule as the initial solution for SA, and the three superior dispatching rules as part of the initial population for GA. Moreover, improved versions of SA and GA are proposed using an insertion algorithm. Extensive computational experiments reveal that the improved versions of SA and GA perform about 95% better than SA and GA. The improved version of GA outperforms the improved version of SA by about 3.5%.展开更多
In design science, these two kinds of problems are mutually nested, however, the nesting could not blind us for the fact that their problem-solving and solution justification methods are different. The ant algorithms ...In design science, these two kinds of problems are mutually nested, however, the nesting could not blind us for the fact that their problem-solving and solution justification methods are different. The ant algorithms research field, builds on the idea that the study of the behavior of ant colonies or other social insects is interesting, because it provides models of distributed organization which could be utilized as a source of inspiration for the design of optimization and distributed control algorithms. In this paper, a relatively new type of hybridizing ant search algorithm is developed, and the results are compared against other algorithms. The intelligence of this heuristic approach is not portrayed by individual ants, but rather is expressed by the colony as a whole inspired by labor division and brood sorting. This solution obtained by this method will be evaluated against the one obtained by other traditional heuristics.展开更多
The effect of nitric oxide（NO） annealing on charge traps in the oxide insulator and transition layer in n-type4H–Si C metal–oxide–semiconductor（MOS） devices has been investigated using the time-dependent bias s...The effect of nitric oxide（NO） annealing on charge traps in the oxide insulator and transition layer in n-type4H–Si C metal–oxide–semiconductor（MOS） devices has been investigated using the time-dependent bias stress（TDBS）,capacitance–voltage（C–V）,and secondary ion mass spectroscopy（SIMS）.It is revealed that two main categories of charge traps,near interface oxide traps（Nniot） and oxide traps（Not）,have different responses to the TDBS and C–V characteristics in NO-annealed and Ar-annealed samples.The Nniotare mainly responsible for the hysteresis occurring in the bidirectional C–V characteristics,which are very close to the semiconductor interface and can readily exchange charges with the inner semiconductor.However,Not is mainly responsible for the TDBS induced C–V shifts.Electrons tunneling into the Not are hardly released quickly when suffering TDBS,resulting in the problem of the threshold voltage stability.Compared with the Ar-annealed sample,Nniotcan be significantly suppressed by the NO annealing,but there is little improvement of Not.SIMS results demonstrate that the Nniotare distributed within the transition layer,which correlated with the existence of the excess silicon.During the NO annealing process,the excess Si atoms incorporate into nitrogen in the transition layer,allowing better relaxation of the interface strain and effectively reducing the width of the transition layer and the density of Nniot.展开更多
基金supported by the National Natural Science Foundation of China(Nos.61106080,61275042)the National Science and Technology Major Project of the Ministry of Science and Technology of China(No.2013ZX02305)
文摘We investigate the effects of NO annealing and forming gas （FG） annealing on the electrical properties of a SiO2/SiC interface by low-temperature conductance measurements. With nitrogen passivation, the density of interface states （DIT） is significantly reduced in the entire energy range, and the shift of flatband voltage, AVFB, is effectively suppressed to less than 0.4 V. However, very fast states are observed after NO annealing and the response frequencies are higher than 1 MHz at room temperature. After additional FG annealing, the DIT and AVFB are further reduced. The values of the DIT decrease to less than 1011 cm-2 eV- 1 for the energy range of Ec - ET 〉/0.4 eV. It is suggested that the fast states in shallow energy levels originated from the N atoms accumulating at the interface by NO annealing. Though FG annealing has a limited effect on these shallow traps, hydrogen can terminate the residual Si and C dangling bonds corresponding to traps at deep energy levels and improve the interface quality further. It is indicated that NO annealing in conjunction with FG annealing will be a better post-oxidation process method for high performance SiC MOSFETs.
文摘The m-machine no-wait flowshop scheduling problem is addressed where setup times are treated as separate from processing times. The objective is to minimize total tardiness. Different dispatching rules have been investigated and three were found to be superior. Two heuristics, a simulated annealing (SA) and a genetic algorithm (GA), have been proposed by using the best performing dispatching rule as the initial solution for SA, and the three superior dispatching rules as part of the initial population for GA. Moreover, improved versions of SA and GA are proposed using an insertion algorithm. Extensive computational experiments reveal that the improved versions of SA and GA perform about 95% better than SA and GA. The improved version of GA outperforms the improved version of SA by about 3.5%.
文摘In design science, these two kinds of problems are mutually nested, however, the nesting could not blind us for the fact that their problem-solving and solution justification methods are different. The ant algorithms research field, builds on the idea that the study of the behavior of ant colonies or other social insects is interesting, because it provides models of distributed organization which could be utilized as a source of inspiration for the design of optimization and distributed control algorithms. In this paper, a relatively new type of hybridizing ant search algorithm is developed, and the results are compared against other algorithms. The intelligence of this heuristic approach is not portrayed by individual ants, but rather is expressed by the colony as a whole inspired by labor division and brood sorting. This solution obtained by this method will be evaluated against the one obtained by other traditional heuristics.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61404098 and 61274079)the Doctoral Fund of Ministry of Education of China(Grant No.20130203120017)+2 种基金the National Key Basic Research Program of China(Grant No.2015CB759600)the National Grid Science&Technology Project,China(Grant No.SGRI-WD-71-14-018)the Key Specific Project in the National Science&Technology Program,China(Grant Nos.2013ZX02305002-002 and 2015CB759600)
文摘The effect of nitric oxide（NO） annealing on charge traps in the oxide insulator and transition layer in n-type4H–Si C metal–oxide–semiconductor（MOS） devices has been investigated using the time-dependent bias stress（TDBS）,capacitance–voltage（C–V）,and secondary ion mass spectroscopy（SIMS）.It is revealed that two main categories of charge traps,near interface oxide traps（Nniot） and oxide traps（Not）,have different responses to the TDBS and C–V characteristics in NO-annealed and Ar-annealed samples.The Nniotare mainly responsible for the hysteresis occurring in the bidirectional C–V characteristics,which are very close to the semiconductor interface and can readily exchange charges with the inner semiconductor.However,Not is mainly responsible for the TDBS induced C–V shifts.Electrons tunneling into the Not are hardly released quickly when suffering TDBS,resulting in the problem of the threshold voltage stability.Compared with the Ar-annealed sample,Nniotcan be significantly suppressed by the NO annealing,but there is little improvement of Not.SIMS results demonstrate that the Nniotare distributed within the transition layer,which correlated with the existence of the excess silicon.During the NO annealing process,the excess Si atoms incorporate into nitrogen in the transition layer,allowing better relaxation of the interface strain and effectively reducing the width of the transition layer and the density of Nniot.
