Papers by Keyword: Microcrystalline Silicon

Abstract: A design of a thin-film solar cell based on microcrystalline and amorphous silicon α-Si:H(n-i-p)/μс-Si:O(n-i-p)/μс-Si:H(n-i-p) was proposed. A physical model and software to calculate the functional characteristics of these solar cells were developed. The numerical simulation results show that the efficiency of the optimized thin-film solar cells may reach up to 16.3 %, open circuit voltage 1.96 V, fill factor 78 %. Improved performance of the non-crystalline solar cell is achieved by an increase in absorbance in the visible range 500 – 800 nm to 40 – 60 % and in the near-infrared range of the solar radiation 800 – 1100 nm to 70 – 75 %.

Abstract: Microcrystalline silicon thin films prepared by plasma enhanced chemical vapor deposition (PECVD). Effects of deposition power on the microstructure properties of the thin films were investigated by Raman spectrometry, Fourier transform infrared absorption spectroscopy (FTIR) and atomic force microscopy (AFM). With increasing deposition power from 100 W to 900 W, the growth rate increased from 0.75Å/s to 2.96Å/s. The Raman spectrometry measurements showed that the peak of all films is nearby at 514 nm. The FTIR spectroscopic analysis exhibit that with power increasing the intensities of both the (Si-H) _n stretching mode component at 2100cm^-1 and wagging mode component at 620cm^-1 increase. The surface morphology of the films using the AFM showed the surface roughness and voids of the films increase with deposition power increasing.

Abstract: Transition films of amorphous hydrogenated silicon (a-Si:H) to microcrystalline silicon (μc-Si:H) have attracted much attention due to the stability, high overall quality for solar cells configuration. Hydrogenated amorphous and microcrystalline silicon films were deposited on glass substrates by a conventional plasma enhanced chemical vapor deposition (PEVCD) varying the substrate temperature from 275 to 350 °C. A silane concentration of 4% and a total flow rate of 100 sccm were used at a gas pressure of 267 Pa. The film thicknesses of the prepared samples were between 700 and 900 nm estimated from the optical transmission spectra. The deposition rates were between 0.2 and 0.3 nm/s. The phase composition of the deposited silicon films were investigated by Raman spectroscopy. The transition from amorphous to microcrystalline silicon was found at the higher temperatures. The crystallization process of the amorphous silicon can be affected by the substrate temperature. A narrow structural transition region was observed from the changes of the crystalline volume fraction. The dark electrical conductivity of the silicon films increased as the substrate temperature increasing.

Abstract: Properties of n-i interface are critical for hydrogenated microcrystalline silicon (μc-Si:H )substrate-type (n–i–p) solar cell as it affects carrier collection, which is visible in the red response . Here, we report a remarkable improvement in visible-infrared responses upon hydrogen plasma treatment （HPT）of n/i interface. We demonstrate that hydrogen plasma treatment in the initial stage of a μc-Si:H i layer growth affects the red response of μc-Si:H solar cell. At the optimal deposition condition, 18% higher short-circuit current density was obtained than its count part without using HPT

Abstract: Microcrystalline silicon (μc-Si:H) film deposited on silicon oxide in a very high frequency plasma enhanced chemical vapor deposition with highly H2 dilution of SiH4 has been investigated by Raman spectroscopy and high resolution transmission electron microscopy. Raman spectroscopy results show that the crystalline volume fraction increases with increasing the hydrogen flow rate and for the hydrogen flow rate of 160 sccm, the crystalline volume fraction reaches to 67.5%. Nearly parallel columnar structures with complex microstructure are found from cross-sectional transmission electron microscopy images of the film. The temperature depend dark conductivity and activation energy are studied in order to investigate the electronic transport processes in the nc-Si films.