IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Photonics Materials Topical Conference Thursday Sessions
       Session PH-ThP

Paper PH-ThP2
Using the Ultrasound Treatment for Grain Boundary Passivation and Improvement of Multi-Si Recombination Properties

Thursday, November 1, 2001, 5:30 pm, Room 134/135

Session: Poster Session
Presenter: Kh. Ismailov, Academy of Sciences of Republic Uzbekistan
Authors: A.V Karimov, Academy of Sciences of Republic Uzbekistan
Kh. Ismailov, Academy of Sciences of Republic Uzbekistan
Sh.N. Bahronov, Academy of Sciences of Republic Uzbekistan
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The photoconverters (PC) has been produced on the base of n and p type multicrystalline silicon with the thickness of 250-300 µm. The technological route of PC included the chemical and mechanical treatments of the wafers (cutting, chemical and mechanical polishing, chemical cleaning and drying), p-n junction was formed by boron thermal diffusion (T~1000-1070 °C) or phosphorous (T~930-970 °C) those penetrated to 0.4-0.7 µm from the solid state reused target. The multi-layer system Ti-Ni-Cu has been used as a collector. The annealing of contacts was carried out at T~ 540-600 °C. The contact frontal topology has been chosen as one- and two-sided grid with the collector buss width of 1mm and contact grid - 0.2 mm. The distance between strips was 3mm. The silicon monoxide (d~ 1000 A) and dioxide SnO@sub 2@ layers were formed by CVD method. This layers were used as antireflection coatings. The total PC area was ~2 cm@super 2@. The samples have been used to study the influence of ultrasonic treatment. The samples have been put into bath with ethanol. On the bottom of the bath was placed the ultrasonic wave sensor (CTS-19). Generator G3-41 with controllable output power exited it. For our case 2.5 MHz frequency and 1 W/cm@super 2@ power were used. The exposure time was chosen experimentally, all measurement was carried out at room temperature. Study of the spectral characteristic of solar cells based on multicrystalline Si under the ultrasonic treatment shown the significant dependence on the exposure time. For example, the 40 minutes exposure leads to photosensitivity increasing. The following increasing of the exposure time up to 120 minutes caused reducing of the photosensitivity on 10-15 %. The spectral characteristics in short-wave spectral range are changed substantially compared to long-wave range. The voltage-current characteristics behave analogously, but they demonstrate the increasing of open circuit voltage (~5%). The dependence of short circuit current on the exposure time in the USW is qualitative agreed with the photocurrent spectral dependence. Totally the changing of the solar cell parameters can be connected with series resistance, and with changing of the material parameters.