Cheng Guanggui

Analysis of the p+/p window layer of thin film solar cells by simulation

The application of a p+/p configuration in the window layer of hydrogenated amorphous silicon thin film solar cells is simulated and analyzed utilizing an AMPS-1D program. The differences between p+?p?i?n configuration solar cells and p?i?n configuration solar cells are pointed out. The effects of dopant concentration, thickness of p+-layer, contact barrier height and defect density on solar cells are analyzed. Our results indicate that solar cells with a p+?p?i?n configuration have a better performance. The open circuit voltage and short circuit current were improved by increasing the dopant concentration of the p+ layer and lowering the front contact barrier height. The defect density at the p/i interface which exceeds two orders of magnitude in the intrinsic layer will deteriorate the cell property.

Research on nano mechanical properties and ultra-structure of yeast cells

Cellular mechanics is a hot field of biological mechanics and biological engineering. The development of the Nano-indentation technique provides a new way for examining the nano-mechanical characteristics of the yeast cells. The nano-indentation properties and the ultra-structure of yeast cells were examined by using the Tribo Indenter in nano-mechanical test Instrument. The largest indentation depth was much less than 10 percent of the diameter of yeast cells, which was measured by the atomic force microscope (AFM). The indentation pit was gradually deepened with the increase of applied loads. The variation amplitudes of nano-hardness and elastic modulus changed with the applied load. The hardness of M22-2 was greater than M22-2/h VDAC at first, whereas it was less than the later one with the increased indentation depth. When yeast cells were on monocrystalline silicon wafer, the elastic modulus of M22-2 was towards an approximate constant of about 0.3854GPa. The elastic modulus of M22-2 was less than that of M-3 at the beginning and was larger than that of M-3 when the indentation depth was larger than 237nm as the elastic modulus of M-3 decreased. The hardness of M22-2 was gradually decreased with the increased indentation depth. The hardness of M-3 was bigger than that of M22-2 at first, whereas was less than that of the latter with the increased indentation depth. The results show that VDAC played an important role on cell function and elasticity of the M22-2 yeast strain supplemented with a human VDAC1 gene better than VDAC1-deficient yeast strain, and also elasticity of the M22-2 yeast better than M-3 yeast strain. The elasticity of the yeast cells on monocrystalline silicon wafer and was better than that on cover glass. By repetitive tests and analyses, the mechanical properties of yeast cells and the load they can sustain were obtained. The experiment proved the feasibility of nano-mechanics property research of yeast cells with the aid of the Tribo Indenter. Nano-indentation technology not only provides useful information for cell physiology and pathology processes, but also brings a new method for the precise quantitative analysis of cell function which is helpful in the surface bionic engineering.

Effect of the Prepared Process on Tribological Properties of Multi-Layer Elastomeric DLC Monolayer

Tribological properties between micro/nano electromechanical systems (MEMS/NEMS) devices are one of the key problems, severely limiting its reliability and stability. However, tribological properties may vary from different surface-dealt procedure. In this paper, structure and tribological property of three samples were discussed: the first one is an elastomeric layer (SEBS), the second is DLC film on an elastomeric substrate prepared by CVD, and the third is DLC film on an elastomeric substrate prepared by filtered cathodic vacuum arc (FCVA). The topography, composition and tribological properties of the two films together with the elastomeric substrate are studied by AFM, Raman and the friction tester (UMT-2), respectively. The result showed that the AFM topography of the sample made by the FCVA(sample 3) was better than that made by CVD(sample2) due to the pure smaller size ion that was provided by FCVA technique. The Raman spectrum of the two samples confirmed the existence of the DLC film on the top surface, and the Id/Ig of sample 3(with 0.36) was twice larger than the sample 2(with 0.19), indicating more sp3 bonds in sample 3; According to the friction tests with different loads and speeds, the tribological property of Sample 3 (with a stable frictional coefficient of 0.1) was better than that of sample 1, while Sample 2 behaved worst in frictional property.