Influence of oxygen content on the crystallinity of MgO layers in magnetic tunnel junctions

With RF sputtering process, Si/Si02/Ta/Ru/Ta/CoFeB/MgO/CoFeB/Ta/Ru structure has been grown on Si （100） substrate. Attempting different targets and adjusting the oxygen dose, the crystallization quality of the MgO layer is studied. The X-ray diffraction measurements demonstrate that crystal structure and crystallization quality of MgO layers are related to the type of target and concentration of oxygen in sputtering process. With the method sputtering Mg in an ambient flow of oxygen, not only the crystallization quality of a normal MgO layer with lattice constant of 0.421 nm is improved, but also a new MgO crystal with lattice constant of 0.812 nm is formed and the perpendicular magnetic anisotropy of CoFeB is enhanced. Also it is found that crystallization quality for both the normal MgO and new MgO is more improved with MgO target and same oxygen dose, which means that this new method is helpful to form a new structure of MgO annealed at 400 ℃ in vacuum. with lattice constant of 0.812 nm. All of the samples were     

热退火对Mn离子注入非故意掺杂GaN微结构、光学及磁学特性的影响

通过Mn离子注入非故意掺杂GaN外延层制备了GaN:Mn薄膜,并研究了退火温度对GaN:Mn薄膜的微结构、光学及磁学特性的影响.对不同退火温度处理后的GaN:Mn薄膜的拉曼谱测试显示,出现了由与离子注入相关的缺陷的局域振动(LV)和(Ga,Mn)N中Mn离子的LV引起的新的声子模.在GaN:Mn薄膜的光致发光谱中观察到位于2.16,2.53和2.92 eV处的三个新发光峰(带),其中位于2.16 eV处的新发光带不能排除来自Mn相关辐射复合的贡献.对GaN:Mn薄膜的霍尔测试显示,退火处理后样品表现出n型体材料特征.对GaN:Mn薄膜的振动样品磁强计测试显示,GaN:Mn薄膜具有室温铁磁性,其强弱受Mn相关杂质带中参与调节磁相互作用的空穴浓度的影响.     

Two-dimensional threshold voltage model of a nanoscale silicon-on-insulator tunneling field-effect transistor

The tunneling field-effect transistor(TFET) is a potential candidate for the post-CMOS era.In this paper,a threshold voltage model is developed for this new kind of device.First,two-dimensional(2D) models are used to describe the distributions of potential and electric field in the channel and two depletion regions.Then based on the physical definition of threshold voltage for the nanoscale TFET,the threshold voltage model is developed.The accuracy of the proposed model is verified by comparing the calculated results with the 2D device simulation data.It has been demonstrated that the effects of varying the device parameters can easily be investigated using the model presented in this paper.This threshold voltage model provides a valuable reference to TFET device design,simulation,and fabrication.     

Two-dimensional threshold voltage model of nanoscale silicon-on-insulator tunneling field-effect transistor

The tunneling field-effect transistor (TFET) is a potential candidate for the post-CMOS era. In this paper, a threshold voltage model is developed for this new kind of device. First, two-dimensional (2D) models are used to describe the distributions of potential and electric field in the channel and two depletion regions. Then based on the physical definition of threshold voltage for the nanoscale TFET, the threshold voltage model is developed. The accuracy of the proposed model is verified by comparing the calculated results with the 2D device simulation data. It has been demonstrated that the effects of varying the device parameters can easily be investigated using the model presented in this paper. This threshold voltage model provides a valuable reference to the TFET device design, simulation, and fabrication.