Papers by Keyword: Mono-Crystalline Silicon

Abstract: Isopropyl alcohol (IPA) is widely used as an additive to enhance the alkaline texturing process of mono-crystalline silicon solar cells currently. However, due to its low boiling point and high volatilization, some negative effects are brought into large scale production especially in stability, cost and environment. In this paper, an IPA-free texturing process was studied by using other additive instead of IPA. The influences of concentration of KOH and additive on etching rate, surface morphology and weighted reflectance were investigated. It is found that the additive has an opposite effect on etching rate and pyramid size compared to KOH. The etching rate and average pyramid size decrease with the concentration of additive increased. The best weight reflectance of 10.8% and lowest average pyramid size of 1.1 um were obtained on mono-crystalline silicon surface by an optimized solution of 1.5 wt% KOH and 1.5 wt% additive at 80oC for 20 minutes. Finally, the effects of KOH and IPA-free additive on the texturing process were also discussed in detail.

Abstract: Isopropyl alcohol(IPA) is widely used as additive to enhance surface structure and reduce the reflectivity of silicon wafers in alkaline texturing process of mono-crystalline silicon solar cells currently. However, due to its low boiling point and high volatilization, some negative effects are brought into large scale production especially in stability, cost and environment. In this paper, Dipropylene glycol(DPG) which has relative high boiling point was tried to substitute IPA as texturing solution additive. The influences of concentration of DPG and NaOH on etching rate, surface morphology and reflectance spectrum were investigated. It is obviously observed that the silicon is prevented from etching reaction by the existence of DPG. The best weight reflectance of 13.6% is obtained on mono-crystalline silicon surface by an optimized solution of 1 wt% NaOH and 1 wt% DPG at 80°C for 20 minutes. Finally, the influencing mechanism of DPG was also discussed in detail.

Abstract: Solar energy directly converses light energy into DC power without fuel, no moving parts, no pollution, and no noise with long life-span more than about twenty years. Its application is extensive and the set up of solar generation can be scattered and in a small amount on demand which is the most available of all renewable energy, and is the most practical and effective energy. There are many kinds of solar cell, such first generation as Mono-crystalline Silicon, Multi-crystalline Silicon, and Amorphous Silicon, the second generation as Film Photovoltaic and the third generation as Dye-Sensitized (DSSCs) etc. The utilization of solar energy is greatly influenced by environmental change with the main reason of solar radiation. This research collects the data from the test of Mono-crystalline Silicon, Multi-crystalline Silicon, and Film Photovaltaic solar cells in different solar radiation, and then conducts the analysis and research thereby. Using the program written by Labview, collect the data of voltage, current, and the power, solar radiation, and temperature emitted by solar cells under test for analysis. And then discuss the results of the collected data by Matlab for data analysis.

Abstract: In this paper, micro-nano scratching experiments were conducted on mono-crystalline silicon wafer to investigate the material removal mechanism of silicon. Two loading methods (increasing-loading and constant-loading) were used. The characteristics of the scratching grooves, and the relationship between the groove size and the load were analyzed by observing the surface torography and measuring the groove. The results show that there are four distinct regimes existed with an increasing scratching load: elastic regime, ductile regime, ductile-brittle regime and brittle regime. The critical load of the transition from ductile to ductile-brittle regime can be considered as 120mN, within which smooth scratching surfaces have been obtained by ductile removal. The scratching load has very significant effects on the groove sizes of the mono-crystal silicon.

Abstract: This paper investigates the “pop-in” behavior of monocrystalline silicon under nanoindentation with a Berkovich indenter. The indentation tests were carried out under ultra-low loads, i.e. 100 μN and 300 μN, with different loading/unloading rates. It was found that with the experimentally determined area function of the indenter tip, the mechanical properties of silicon can be accurately calculated from the load-displacement data, that a pop-in event represents the onset of phase transition, and that a lower loading rate favours a sudden volume change but a rapid loading process tends to generate a gradual slope change of the load-displacement curve.