| As the fossil energy of the whole world is running out and the global environment is worse and worse, the development and applicating of the renewable energy is becoming more and more important and urgent. Because solar energy is enormous and clean, people have been focused on how to make use of it with high efficiency. As for China, making use of solar energy with high efficiency to get rid of the dependence of the imported fossil energy is a very important for us to increase the energy security and enhance our international influence.Solar theral generating technology, which is a very promising technology, is a method to convert solar energy to electric energy indirectly. It can collect solar radiation over a very large area, transform the solar energy to electric energy with high efficiency, and be easy to store and transport the electric energy for the next step. However, the current overall convertion efficiency for the solar thermal generating system is only about 14%, which is mainly caused by the reflection on the thermal receiver surface. Moreover, the anti-reflecting coaing can only absorb the visible light, so a large amount of solar energy in the near UV and near IR spectra is wasted. This part of solar energy cannot be absorbed by heat transfer fluid, so the efficiency of the light to heat energy transform will be low.Surface microstructured silicon, also named black silicon, has been considered as a revolutionary new material in the 21st century. This new material can absorb the light under ultra-wide spectrum region. From UV to near infrared, there is almost no reflectance on the black silicon surface. It can be used as a perfect anti-reflecting coaing in the solar harvest applications. However, the current black silicon fabrication is based on regular silicon wafer, which is too thick to be bent or flexible, so it cannot be applicated on the solar thermal receiver tube. Furthermore, the thick substrate of the black silicon also affects its heat transfer property.In order to improve the overall efficiency of the solar thermal generating system, people have to find a high-efficiency absorbing material to absorb the solar power as much as possible and to transfer the energy to heat transfer fluid. Black silicon is a good absorbing material, but it cannot be used on the solar thermal system suffering from its thickness and lack of flexibility. Therefore, it is very important and necessary to develop a novel flexible black silicon which has good heat transferring property and high absorptance.Based on the researches on the solar thermal generating technology and surface microstructured silicon, the optical properties of the regular surface microstructured silicon was analyzed by using the scalar and vectorial diffraction theory; the energy band structure and the opto-electrical properties were also studied. The properties of ultra-thin flexible black silicon were also studied. After that, the regular and ultra-thin flexible black silicon were fabricated, and their absorbing spectra were measured. The reason why flexible black silicon has ultra-high absorptance was discussed, and preliminary experiments were carried out to verify the absorbing and heat-transferring properties. At last, the massive inductrial fabrication method of the black silicon was studied by using the negative refractive material and the superlens. The detailed constents were listed as below:1) The scalar diffraction theory was used to get the optical properties of the light at the semiconductor surface. Then based on the unique structures of the black silicon, the Rigorous Coupled Wave Analysis (RCWA) was used to calculate the reflective spectra of 3 different sizes of the black silicon, and the incident angle dependence of the reflectance was also talked about. After that, the Finite Difference Time Domain (FDTD) method was used to get the absorptance of the black silicon with different sizes.2) Based on the energy band theory, the band-gap narrowing and generation of mid-band inside the band-gap were discussed to explain the high absorptance of black silicon at below band-gap region. The influence of sulfur concentration on the absorbing ability of the black silicon at the IR wavelength was also studied. The light-to-electricity conversion inside the black silicon was discussed from the aspect of semiconductor physics, and the generation and life time of carriers inside the semiconductor were also studied.3) The optical properties of the ultra-thin flexible black silicon were analysed from the scalar and the vectorial diffraction theories, and its reflectance and absorptance were calculated and compared with that of the regular black silicon. The absorptance of flexible black silicon was supposed to be a little lower than that of the regular black silicon. Then its heat transferring properties were discussed and the heat transferring speed was calculated to compare with that of other materials. The results showed that it could fuction as a very good light-absorbing and heat-transferring layer.4) Then the method of femtosecond laser pulses assisted with the etching gas was chosen to fabricate the black silicon on commercial silicon wafer. The SEM pictures showed great microstructures on the surface of silicon wafer. The absorbing spectrum was measured using a spectrophotometer and the results indicated that the absorptance of the black silicon was very high under a wide spectrum region. Even in the sub-bandgap region, the absorptance was as high as 80%, which verified the theoretical analysis and experimental method were right. There were also several shortcomings existing in the processes of the experiment. So the experimental setup was improved by using the auto-scanning method instead of the single point method. The results showed the new method was much more efficient than the original method.5) Using the auto-scanning method, the microstructures were fabricated on the SOI wafer. We use the hydrofluoric (HF) acid to etch the middle layer of the SOI then the top layer with microstructures could be splitted. So the ultra-thin flexible black silicon was obtained. We can see uniform microstructures on the surface from the SEM pictures. The absorption spectrum was as good as that of regular black silicon. The dependence of absorptance with the incident angle of light was also studied, and the reason of ultra-high absorptance was discussed. The results verified the feasibility of the novel black silicon as an efficient flexible absorbing layer.6) The optical medel of the solar trough was analyzed, and the absorption efficiency of the black silicon over the whole soalr spectrum was calculated, which was as high as 91.5%. Preliminary experiments were carried out to verify the light-absorbing and heat-transferring effect of the flexible black silicon. At last the solar trough generating system with the black silicon absorbing layer was proposed.7) The negative reflective matetial and the superlens were studied theritically and the FDTD method was used to simulate the enhancement of resolution in lithography system by applying the superlens. The simulation results showed that 200-nm grating structure can be imaged perfectly. Combined with the semiconductor fabrication technologies, the massive industrial black silicon fabrication method was studied by using the negative reflection technology. And the technical map was developed.
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