**5. Conclusion**

378 Solar Cells – Thin-Film Technologies

**Jsc: 2.15(mA/cm2**

**Voc : 0.54 (V) FF:0.4451 Eff:0.5236 (%)** **)**

**(b)** 

**0 0.1 0.2 0.3 0.4 0.5 0.6 0.7**

**Voltage (V)**

**300 400 500 600 700 800 900 1000**

**Wavelength (nm)** 

Fig. 28. (a) Photocurrent-voltage characteristics under AM 1.5 exposure condition and (b) QE spectra under -1V biased conditions of Si thin-film solar cells using a 1µm-thick μc-

**0**

Si:H:Cl layer by high-density microwave plasma source.

**0.1**

**0.2**

**0.3**

**0.4**

**Quantum Efficiency (%)** 

**0.5**

**-1 V** 

**0 V** 

**0.6**

**0.7**

**0.8**

**0**

**0.5**

**1**

**(a)** 

**1.5**

**Current density (mA/cm2**

**)**

**2**

**2.5**

**3**

The highly photoconductive and crystallized μc-Si:H:Cl films with less volume fraction of void and defect density were synthesized using the high-density and low-temperature microwave plasma source of a SiH2Cl2-H2 mixture rather than those from SiH4 while maintaining a high deposition rate of 27 Å/s. The μc-Si:H:Cl film possesses a μc-Si and a-Si mixture structure with less volume fraction of voids. The role of chlorine in the growth of μc-Si:H:Cl films is the suppression of the excess film crystallization at the growing surface. H termination of growing surface is more effective to suppress the defect density rather than that of Cl termination. The fast deposition of the μc-Si:H:Cl film with low defect density of 3-4 ×1015 cm-3 is achieved with reducing Cl concentration during the film growth. Both a-Si:H:Cl and µc-Si:H:Cl films show

**18** 

*Ukraine* 

**Chemical Surface Deposition** 

**of CdS Ultra Thin Films from** 

Solar cells (SC) are the most effective devices that allow direct one-stage conversion solar energy into electricity from the view of energy. The last yers tendency in traditional energetic forced to direct a significant part of research on the establishment of modern technology for production available and effective thin film SC that would not require the use of high temperature and pressure, a large number of rare and expensive materials. At the same time, to find ways for increase the conversion efficiency of solar energy it is necessary to understand the processes that occur in the elements. Therefore it is necessary to establish a correspondence between characteristics of elements and main structural, electronic and optical properties of initial semiconductor films. Therefore, the investigation of CdS thin films deposition process with desire photoelectric properties and fabrication on

CdS is the main material for buffer layer in thin-film CdTe and Cu(In, Ga)Se2 solar cells. It has a high photosensitivity and absorption, favorable energy band gap (Eg) 2,4 eV and photoconductivity () 102 Om-1cm-1 and does not change the properties with SC surface temperature increase during the work. One more peculiarity of this material is absence of the hole conduction due the acceptor additives and point defects recombination. Effective lifetime of the main carriers is very large (10...100 ms), that causes a initial photocurrent increase up to 105 times (Hamakawa, 2002). An important advantage of CdS thin films use in SC is possibility of their synthesis by different methods, including chemical deposition from solution which has significant preference over others: 1) grown nanocrystalites with a form close to spherical, while the electrochemical deposition - nonspherical (Jager-Waldau, 2004); 2) CdS thin films deposited from solution have structural, optical and electrical parameters thet do not inferior parameters of films received by other methods, but used equipment is available, simple, does not require use of the high temperatures and pressures compared, for example, with the vacuum evaporation or ion (sputtering or pulverization, spraying) methods; 3) the method is not explosive and lowtoxic, compared with the vapor deposition methods; 4) enable control of the film growth and dynamically change the fabrication conditions for polycrystalline or smooth solid

**1. Introduction** 

films.

their base thin-film SC have great significance.

H. Il'chuk, P. Shapoval and V. Kusnezh

**Aqueous Solutions** 

*Lviv Polytechnic National University* 

high photoconductivity of 10-5 S/cm under 100 mW/cm-2 exposure, are the possible materials for Si thin-film solar cells. The performance of p-i-n solar cell from µc-Si:H:Cl films using the high-density microwave plasma source was confirmed for the first time.
