IMPROVEMENT OF THE PASSIVATION PROPERTIES OF SiO₂ FILMS, GROWN BY THE METHOD OF RAPID THERMAL ANNEALING, AFTER CHEMICAL RCA TREATMENT

As it is known, increasing the efficiency of silicon solar cells is one of the most important tasks in modern alternative energy industry. Optimization of the antireflection and passivation layer is the most economical way to increase efficiency. In this work, the effect of pretreatment on the passivation properties of silicon dioxide (SiO₂) films grown by rapid thermal processing (RTP) at annealing temperatures of 900 and 950°C in a dry oxygen atmosphere, was studied. The growth of thin films of SiO₂  on the surface of monocrystalline silicon wafers was carried out in the AS-ONE 150 rapid thermal annealing chamber (France). Measurements of the lifetime of minority charge carriers by the non-contact microwave method showed that the best passivation of the samples is achieved by applying a preliminary three-stage chemical cleaning (RCA) of the surface of the n-type silicon wafers. IR spectroscopy confirmed the formation of a SiO₂  layer by the presence of an intense maximum at 1071 cm^-1, which was attributed to stretching vibrations of the "tensioncompression" type. The results of calculations of the optical constants of the obtained SiO₂  films using the reflection spectra and the SCOUT software show the presence of a silicon dioxide whose refractive index and extinction coefficient are close to the reference.

1. Nussupov K.K., Beisenkhanov N.B., Keiinbay S., Sultanov A.T. Silicon carbide synthesized by RF magnetron sputtering in the composition of a double layer antireflection coating SiC/MgF2 // Optical Materials, 2022, vol. 128, no. 112370.

2. Bonilla R.S., Hoex B., Hamer P., Wilshaw P.R. Dielectric surface passivation for silicon solar cells: A review. // Phys. Status Solidi A., 2017, no. 1700293.

3. Green M.A. The Passivated Emitter and Rear Cell (PERC): From conception to mass production // Solar Energy Materials & Solar Cells, 2015, pp. 190–197.

4. Cacciato A., Duerinck F., Baert K., Moors M., Caremans T., Leys G., Keersmaecker K.D., Szlufcik J. Investigating manufacturing options for industrial PERL-type Si solar cells // Solar Energy Materials & Solar Cells, 2013, pp. 153–159.

5. Mandal N. C., Biswas S., Acharya S., Panda T. Study of the properties of SiOx layers prepared by different techniques for rear side passivation in TOPCon solar cells / Materials Science in Semiconductor Processing, 2020, p. 119.

6. Fukuda H., Yasuda M., Iwabuchi T. Kinetics of Rapid Thermal Oxidation of Silicon // Applied Physics, 1992, pp. 3436–3439.

7. Liu C. P., Chang M.W., Chuang C.L. Effect of rapid thermal oxidation on structure and photoelectronic properties of silicon oxide in monocrystalline silicon solar cells // Current Applied Physics, 2014, pp. 653-658.

8. Gad K.M., Vössing D., Balamou P., Hiller D., Stegemann B., Angermann H., Kasemann M. Improved Si/SiOx interface passivation by ultra-thin tunneling oxide layers prepared by rapid thermal oxidation // Applied Surface Science, 2015, vol. 353, pp. 1269–1276.

9. Kern W. The Evolution of Silicon Wafer Cleaning Technology // Journal of the Electrochemical Society, 1990, vol. 137, no 6, pp. 1887–1892.

10. Gao L., Lemarchand F., Lequime M. Refractive index determination of SiO2 layer in the UV/ Vis/NIR range: spectrophotometric reverse engineering on single and bi-layer designs // J. Europ. Opt. Soc. Rap. Public., 2013, vol. 8, no 13010.

11. Prasad I., Chandorkar A.N. Spectroscopy of silicon dioxide films grown under negative corona stress // Journal of Applied Physics, 2003, vol. 94, no 4, pp. 2308–2310.

12. Samitier J., Marco S., Ruiz O., Morante J.R., Esteve-Tinto J., Bausells J. Analysis by FTIR spectroscopy of SiO,-polycrystalline structures used in micromechanics: stress measurements // Sensors and Acrualors A, 1992, vol. 32, pp. 347–353.