Analysis of oxide bulk trapped charge distribution and densities from photo injection characteristics of oxide-nitride-oxide (ONO) structures
The thickness of ONO inter-poly dielectrics dominates the program and erase speed of a flash memory cell transistor with a stack gate structure. Therefore, as flash devices shrink, it is important to prevent the degradation in reliability while scaling down the thickness of the oxide. However, the thickness of the bottom oxide formed on a heavily doped poly-silicon cannot be easily reduced because of its high defect density due to a high concentration of dopants in the floating gate and an enhancement of the oxide thickness caused by oxidation of the doped polysilicon [1]. In order to overcome these problems, advanced LPCVD technology has been introduced, but the LPCVD oxide films still have many defect densities in comparison with thermal oxide films. In this work, the bulk trapped charges distribution and density in the bottom LPCVD oxide were quantitatively investigated by photocurrent-voltage characteristics. In addition, we found that the defect density and distribution in the bottom LPCVD oxide were remarkably decreased using post plasma oxidation.
Determination of insulator bulk trapped charge densities and centroids from photocurrent‐voltage charactersitcs of MOS structures
A new rapid technique for determining the density and centroid of trapped space charge in MOS structures is described. Photocurrent‐voltage characteristics for both the metal‐oxide and Si‐oxide interfaces are used to determine the internal fields due to bulk trapped charge and, hence, its density and centroid. An experimental example of this technique is shown for a MOWOS (metal‐SiO2‐W‐SiO2‐Si) structure where a layer of approximately 1014 W atoms/cm2 deposited 80 or 42 A from the Si‐SiO2 interface and charged by internal photoemission is investigated. This technique is compared to others in terms of its direct, rapid, minimally perturbing, low‐current and low‐field characteristics.
Research on automatic tracking solar power system
The paper elaborates the features of solar power. On the foundation of it, it analyses the composing, the theory and the features of solar power system of automatic tracking, analyzing the function of mental composing and the important technology, making a compartment of the amount of generation of solar power system of automatic tracking and that of common solar power system.