Titanium oxide passivation film preparation method and solar energy cell prepared through utilizing titanium oxide passivation film preparation method

Abstract

The invention discloses a titanium oxide passivation film preparation method. The method comprises steps that an electron beam deposition method is utilized to deposit a metal titanium film with certain thickness at the surface of a silicon chip after pretreatment, then annealing is carried out in the oxygen atmosphere, and cooling in the nitrogen atmosphere is then carried out. The electron beamdeposition method and the metal titanium film are utilized to directly carry out oxidation of the metal titanium film to form a titanium oxide film, compared with the ALD / CVD process, equipment requirements are low, an operation mode and the operation flow are simpler, adjustment on the thickness of the metal titanium film and the oxidation process is facilitated to adapt to different silicon chippassivation demands, the titanium oxide passivation film and other passivation medium layers can excellently form laminated layers, so the better passivation result is realized; the method is suitable for a thermal evaporation method, a magnetron sputtering method to deposit the metal titanium film; deposition of microscale active metal can be easily realized, and thereby doped modification of the final titanium oxide film is realized.

Description

technical field [0001] The invention relates to a method for preparing a passivation film of a solar cell, in particular to a preparation method of a passivation film of titanium oxide. Background technique [0002] The thin film of crystalline silicon substrate has become an important development trend to further improve the photoelectric conversion efficiency of crystalline silicon solar cells and reduce the production cost. With the reduction of the thickness of the silicon substrate, generally by designing a new type of light-trapping structure on the surface of the silicon to enhance the utilization of light, so as to make up for the lack of thickness of the silicon wafer. Correspondingly, designing a new surface passivation film to reduce the surface recombination rate of the textured structure has become an important means to improve the photoelectric conversion efficiency of this type of solar cell. On traditional crystalline silicon, dielectric layers such as titan...

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Problems solved by technology

[0003] The existing preparation techniques of functional titanium oxide passivation films mainly include atomic layer deposition (ALD), chemical vapor deposition (CVD), sol-gel (sol-gel), physical sputtering deposition, etc. For each preparation process There are certain limiting factors

Atomic layer deposition technology generally uses an organic titanium source such as titanium tetrachloride as a precursor, water as an oxidant, and nitrogen as a transport gas. The deposition temperature is about 100 ° C. The final titanium oxide is controlled by controlling the number of cycles during the deposition process. Thickness, the initial passivation effect of the titanium oxide film obtained by this process is poor, and it is necessary to further activate the passivation of the silicon surface through a post-annealing process at about 250 °C in a nitrogen atmosphere to achieve the ideal passivation effect; the existing literature The best passivation effect of titanium oxide reported can control the recombination rate of the silicon surface at about 2.5cm / s. To achieve this effect, it needs to be exposed to light for a long time after nitrogen annealing, and the use of ALD to prepare titanium oxide thin films is very difficult for equipment. 1. The deposition process requires high requirements, while the equipment cost is expensive and the universality is low; in addition, the existing ALD / CVD deposition technology needs to use high-purity organic titanium source as the precursor, which is expensive, and the organic source will be used later. In the annealing process, the pollution of carbon impurities will inevitably be introduced, which will easily affect the preparation of the final battery device, and the passivation effect of the silicon nitride / titanium oxide stack is not particularly good, the passivation effect is low, and it is not It is easy to dope the subsequent film to adjust its photoelectric performance; if the titanium oxide film prepared by ALD / CVD method does not pass the annealing process, the film has poor adhesion to the silicon substrate

Although the titanium oxide film prepared by the sol-gel method can meet the requirements of low-temperature preparation, the synthesis process of its precursor is complicated, and the final passivation effect on the silicon surface is far less than that of ALD / CVD and other processes; The poor contact between TiOx and Si affects the photoelectric conversion efficiency of crystalline silicon solar cells

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