A series of slow drain current recovery transients at different gate biases after a short-term stress are observed in an AIGaN/GaN HEMT. As the variation of the time constants of the transients is small, the working t...A series of slow drain current recovery transients at different gate biases after a short-term stress are observed in an AIGaN/GaN HEMT. As the variation of the time constants of the transients is small, the working trap is determined to be electronic. A numerical simulation verifies this conclusion and reproduces the measured transients. The electron traps at different spatial positions in the device-on the ungated surface of the AIGaN layer,in the AIGaN barrier, and in the GaN layer are considered;corresponding behaviors in the stress and the transients are discussed;and for the simulated transients, agreement with and deviation from the measured transients are explained. Based on this discussion, we suggest that the measured transients are caused by the combined effects of a deep surface trap and a bulk trap in the GaN layer.展开更多
In this paper, an efficient multigrid fictitious boundary method （MFBM） coupled with the FEM solver package FEATFLOW was used for the detailed simulation of incompressible viscous flows around one or more moving NAC...In this paper, an efficient multigrid fictitious boundary method （MFBM） coupled with the FEM solver package FEATFLOW was used for the detailed simulation of incompressible viscous flows around one or more moving NACA0012 airfoils. The calculations were carded on a fixed multigrid finite element mesh on which fluid equations were satisfied everywhere, and the airfoils were allowed to move freely through the mesh. The MFBM was employed to treat interactions between the fluid and the airfoils The motion of the airfoils was modeled by Newton-Euler equations. Numerical results of experiments verify that this method provides an efficient way to simulate incompressible viscous flows around moving airfoils.展开更多
文摘A series of slow drain current recovery transients at different gate biases after a short-term stress are observed in an AIGaN/GaN HEMT. As the variation of the time constants of the transients is small, the working trap is determined to be electronic. A numerical simulation verifies this conclusion and reproduces the measured transients. The electron traps at different spatial positions in the device-on the ungated surface of the AIGaN layer,in the AIGaN barrier, and in the GaN layer are considered;corresponding behaviors in the stress and the transients are discussed;and for the simulated transients, agreement with and deviation from the measured transients are explained. Based on this discussion, we suggest that the measured transients are caused by the combined effects of a deep surface trap and a bulk trap in the GaN layer.
基金Supported by National 863 Plan Project of Ministry of Science and Technology of China under Grant No. 2006AA09Z354National Natural Science Foundation of China under Grant No. 10672101.
文摘In this paper, an efficient multigrid fictitious boundary method （MFBM） coupled with the FEM solver package FEATFLOW was used for the detailed simulation of incompressible viscous flows around one or more moving NACA0012 airfoils. The calculations were carded on a fixed multigrid finite element mesh on which fluid equations were satisfied everywhere, and the airfoils were allowed to move freely through the mesh. The MFBM was employed to treat interactions between the fluid and the airfoils The motion of the airfoils was modeled by Newton-Euler equations. Numerical results of experiments verify that this method provides an efficient way to simulate incompressible viscous flows around moving airfoils.
