ELECTROCHEMICAL HYDROGENIZATION OF THE FRONTAL SURFACE OF SOLAR CELLS AND THEIR RESEARCH BY MASS SPECTROSCOPY

Abstract

Purpose. Texturing of the silicon surface, both by chemical and electrochemical etching, is an integral part of the technology of modern high-performance silicon solar cells. The texture on the front surface of the solar cells not only reduces reflection losses, but also helps to capture long-wave light in the SC structure, thereby expanding its operating spectral range and increasing the short-circuit current. In this regard, the study of the PSi layer in a nanotexture by mass-spectroscopy on the functional properties of the frontal silicon surface, which was pre-textured, is of particular interest. Methodology. The study of all stages of formation of hydrogenated porous structure and identification of technological patterns that affect the characteristics of the obtained nano-, meso-, macropores are very important, because most of the porous parameters are laid at the stage of formation of nucleation (seed) centers. In order to improve the passivating properties of PSi layers used in solar cells, the process of electrochemical hydrogenation of PSi as on p - type silicon substrates with a resistivity of 0.1 ÷ 10 Ohmsm also on substrates with a formed emitter junction n+- p of conductivity was studied. Various solutions were used as the electrolyte, such as (HF: C2H5OH=1: 1), (HF: C2H5OH=1:2) and so on. The current density and anodizing time varied over a wide range of values, which allowed the formation of PSi layers with different porosity and thickness. A solution of HF: C2H5OH = 1: 1 was used as the electrolyte. The anodizing current and time varied over a wide range of values to obtain PSi layers with different porosity and thickness. To determine the conditions of the process of electrochemical hydrogenation of PSi during its cathodic polarization, potentiostatic current-voltage curves of the system Pt (anode)-electrolyte-porous silicon/ silicon (cathode) for electrolytes with different chemical composition were taken. Finding. Comparison of the surface appearance of Baysix type multicrystalline silicon samples before and after hydrogen hydrogenation in an electrolyte based on hydrofluoric acid ((HF: C2H5OH=10:1), (HF:C2H5OH=10:2) and so on), both in the secondary ion Spectra and in the image of the distribution of elements over the surface (mass spectral ion microscope and Ion microzond mode). Originality. We get a 2D image (size 200x200 microns) of the surface of the current of secondary ions H+ hydrogen and 2D image of the secondary ion current of molecular SiH2+ the surface of a Baysix type multicrystalline substrate passivated with hydrogen by hydrogenation, which is comparable to the optical image of a pure silicon surface that has been hydrogenated. From the form of 2D-ion images, as well as their individual parts, it can be seen that all the difference in the current intensity of the secondary ions is due to the topography of the surface of the samples. Practical value. The prospects of creating efficient solar cells using multifunctional multi-textures of porous silicon are shown. References 24, figures 6.