**8. Acknowledgment**

Part of this work has been performed within the EC funded RISE project (FP6-INCO-509161). The authors want to thank the EC for partially funding this project.

### **9. References**

74 Solar Cells – Thin-Film Technologies

The values Voc=316 mV, Isc=0,117 mA/cm2, fill factor =0,277, upon 50mW/cm2 illumination are compared with the values: Voc=190 mV, Isc=2,08 mA/cm2, fill factor = 0,295; upon 120mW**/cm2** illumination (Katayama et al. 2004) made with electrochemical deposition technique. Maybe doping of the ZnO films with In, Ga and Al (Machado et al., 2005, Kemell et al., 2003) will decrease the resistivity and increase the electro conductivity of

The performance of the Cu2O Schottky barrier solar cells are found to be dependent on the starting surface material, the type of the junction, post deposition treatment and the ohmic contact material. Better solar cells have been made using an heterojunction between Cu2O and n-type TCO of ZnO. It is a suitable partner since it has a fairly low work function. Our investigation shows that the ZnO layer improves the stability of the cells. That results in a device with better performances despite of the Schhotky barrier solar cells (Cu2O/SnO2). First, the cells show photovoltaic properties without annealing, because potential barrier was formed without annealing. To improve the quality of the cells, consequently to improve the efficiency of the cells, it has to work on improving the quality of ZnO and Cu2O films, because they have very high resistivity, a factor which limits the cells performances. Doping of the ZnO films with In, Ga and Al will decrease the resistivity of the deposited films and increase their electroconductivity. SEM micrographs show that same defects are present in the films which act as recombination centers. Behind the ohmic contact, maybe one of the reason for low photocurrent is just recombination of the carriers and decreasing of the hole cocentracion with the time. The transmittivity in a visible region have to increase. Also, it is necessary to improve the ohmic contact, consequently to increase the short circuit current density (*Isc*). For further improvement of the performances of the cells maybe inserting of a buffer layer at the heterojunction between Cu2O and ZnO films will improve the performance of the cells by eliminating the mismatch defects which act as recombination centers. Also it will be protection of reduction processes that maybe exists between ZnO and

Fig. 28. 1/C2 vs applied voltage of Cu2O/ZnO/SnO2 cell

**7. Conclusion** 

Cu2O.

the films, consequently and the short circuit current density of the cells.


Rai B.P., (1988) Cu2O Solar Cells *Sol. Cells* 25 p.265.


**4** 

L. Fu

*P. R. China* 

**Application of Electron Beam Treatment** 

*College of Materials Science, Northwestern Polytechnical University, Xian,* 

Solar cell attracts more and more attentions recently since it transfers and storages energy directly from the sun light without consuming natural resources on the earth and polluting environment. In 2002, the solar industry delivered more than 500 MW per year of photovoltaic generators. More than 85% of the current production involved crystalline silicon technologies. These technologies still have a high cost reduction potential, but this will be limited by the silicon feedstock (Diehl et al., 2005; Lee et al., 2004). On the other hand the so-called second generation thin film solar cells based on a-Si, μc-Si, Cu(In,Ga)(Se,S)2, rare earth or CdTe have been explored(Shah et al.,2005; Li et al.,2004). Crystalline silicon on glass (CSG) solar cell technology was recently developed by depositing silicon film on a glass substrate with an interlayer. It can addresses the difficulty that silicon wafer-based technology has in reaching the very low costs required for large-scale photovoltaic applications as well as the perceived fundamental difficulties with other thin-film technologies (M. A. Green et al., 2004). This technology combines the advantages of standard silicon wafer-based technology, namely ruggedness, durability, good electronic properties and environmental soundness with the advantages of thin-films, specifically low material use, large monolithic construction and a desirable glass substrate configuration. This Chapter will descript research about the polycrystalline silicon thin film absorber based on CSG technology with high efficiency. Line shaped electron beam recrystallized polycrystalline silicon films of a 20μm thickness deposited on the low cost borosilicate glasssubstrate, which are the base for a solar cell absorber with high efficiency and throughput. It is known that the morphology of polycrystalline silicon film and grain boundaries have strong impact on the photoelectric transformation efficiency in the later cell system. Thus, this study concentrates on the influence of recrystallization on the silicon-contact interface

Fig. 1 shows the schematic illustration of the silicon solar cell used in this work. The substrate of polycrystalline silicon thin film is Borosilicate glass, which is 10×10×0.07cm3 in size. A pure tungsten layer of 1.2µm was sputtered on the glass substrate at DC of 500W in

**1. Introduction** 

and the surface morphology.

**2. Experiment methods** 

**in Polycrystalline Silicon Films** 

 **Manufacture for Solar Cell** 

*State Key Laboratory of Solidification Processing* 

Wang L. and Tao M. (2007) Fabrication and Characterization of p-n Homojunctions in Cuprous Oxide by Electrochemical Deposition, *Electrochemical and Solid-State Letters*, 10 (9) H248-H250
