Production of amorphous silicon / p-type crystalline silicon heterojunction solar cells by sputtering and PECVD methods

Download
2011
Eygi, Zeynep Deniz
Silicon heterojunction solar cells, a-Si:H/c-Si, are promising technology for future photovoltaic systems. An a-Si:H/c-Si heterojunction solar cell combines the advantages of single crystalline silicon photovoltaic with thin-film technologies. This thesis reports a detailed survey of heterojunction silicon solar cells with p-type wafer fabricated by magnetron sputtering and Plasma Enhanced Chemical Vapor Deposition (PECVD) techniques at low processing temperature. In the first part of this study, magnetron sputtering method was employed to fabricate a-Si:H thin films and then a-Si:H/c-Si solar cells. Amorphous silicon (a-Si:H) films were grown on glass in order to perform electrical and optical characterizations. The J-V characteristics of the silicon heterojunction solar cells were analyzed as a function of a-Si:H properties. It was shown that a-Si thin films with well-behaved chemical and electronic properties could be fabricated by the magnetron sputtering. Hydrogenation of the grown film could be achieved by H2 introduction into the chamber during the sputtering. In spite of the good film properties, fabricated solar cells had poor photovoltaic parameters with a low rectification characteristic. This low device performance was caused by high resistivity and low doping concentration in the sputtered film. The second part of the thesis is dedicated to heterojunction solar cells fabricated by PECVD. In this part a systematic study of various PECVD processing parameters were carried out to optimize the a-Si:H(n) emitter properties for the a-Si:H(n)/c-Si(p) solar cell applications. In the next stage, a thin optimized a-Si:H(i) buffer layer was included on the emitter side and on the rear side of the c-Si(p) to improve the surface passivation. Insertion of an a-Si:H(i) buffer layer yielded higher high open circuit voltage (Voc) with lower fill factor. It was shown that high Voc is due to the efficient surface passivation by the front/rear intrinsic layer which was also confirmed by the measurement of high effective lifetime for photo-generated carriers. Low fill factor on the other hand is caused by increasing resistivity of the solar cells by inserting low conductivity a-Si:H(i) layers.

Suggestions

Analysis of boron doped hydrogenated amorphous silicon carbide thin film for silicon heterojunction solar cells
Salimi, Arghavan; Turan, Raşit; Department of Micro and Nanotechnology (2019)
Silicon based solar cells are the dominant type of solar cells in the photovoltaic industry. Recently, there have been increasing efforts to develop c-Si solar cells with higher efficiency and lower cost. Among them, silicon heterojunction solar cell (SHJ) is attracting much attention because of its superior performance values demonstrated at both R&D and industrial levels. One of the common limiting criteria is the recombination at the front side which can be solved by providing proper passivation at the f...
Fabrication and investigation of extremely thin CdTe absorber layer solar cells
Hosseini, Arezoo; Erçelebi, Ayşe Çiğdem; Turan, Raşit; Department of Physics (2016)
Extremely thin absorber layer (ETA) solar cells aim to combine the advantages of using very thin and cheaply produced absorber layer on nano structured substrates with stability of all-solid-state solar cells. This type of photovoltaic devices use a nano structured interpenetrating heterojunction of thin light-absorbing layer at the interface between an n- and p-type semiconductors. N-type nano structured TiO2 layer is deposited on a Transparent Conducting Oxide coated glass (TCO) substrate, following with ...
Design of high-efficiency dye-sensitized nanocrystalline solar cells
Yavuz, Halil İbrahim; Özenbaş, Ahmet Macit; Erçelebi, Ayşe Çiğdem; Department of Metallurgical and Materials Engineering (2014)
Nanocrystalline dye sensitized solar cells (DSSC) technology continues to develop as a better alternative to the silicon based solar cells, which are commercialized. This study aims at finding low cost and highly efficient DSSC design and production methods via examination of effects of both photoanode structure and photon-electron generation mechanism on photoanode layers. This will contribute to the commercialization of DSSC technology. Photoanode structure is examined in four groups; transparent conducti...
Fabrication of Si nanocrystals in an amorphous SiC matrix by magnetron sputtering
Gencer Imer, A.; Yıldız, İlker; Turan, Raşit (Elsevier BV, 2010-7)
Si nanocrystals embedded in a wide bandgap material have been of interest for various electronic devices, including third-generation solar cells with efficiency values exceeding theoretical limits. In this work, Si-rich amorphous SiC layers with different Si contents were fabricated by the RF magnetron sputtering deposition technique. Si nanocrystal formation was induced by a high-temperature annealing process in a series of samples with different Si contents controlled by the DC power applied to the Si tar...
A numerical analysis of interdigitated back contacted silicon solar cells
Acar, Beran; Yerci, Selçuk; Turan, Raşit; Department of Electrical and Electronics Engineering (2018)
The state-of-the-art solar cells manufactured using crystalline silicon (c-Si) are highly cost-effective, competing with fossil fuel-based energy sources. However, relatively more complex cell structures (i.e. interdigitated back contact, IBC) need to be developed to further increase the efficiency/cost ratio. In this thesis, the effects of structural parameters such as cell dimensions, metal contact geometry and contact resistances on the efficiency of IBC and bifacial IBC silicon solar cells were studied ...
Citation Formats
Z. D. Eygi, “Production of amorphous silicon / p-type crystalline silicon heterojunction solar cells by sputtering and PECVD methods,” Ph.D. - Doctoral Program, Middle East Technical University, 2011.