The Experts below are selected from a list of 58209 Experts worldwide ranked by ideXlab platform
Martin A Green - One of the best experts on this subject based on the ideXlab platform.
-
effects of high temperature incubation on solid phase crystallisation of silicon films and properties of polycrystalline silicon thin film solar cells on glass
Photovoltaic Specialists Conference, 2011Co-Authors: Yuguo Tao, Sergey Varlamov, R J Egan, Michael Wolf, O Kunz, T Soderstrom, Martin A GreenAbstract:High temperature, 640 °C or 680 °C, and 8 to 60 min long treatment was applied to amorphous Si films on glass prior to solid-phase crystallisation (SPC) at 600 °C to selectively enhance and shorten the “incubation-only” period in the SPC process. Effects of such enhanced-incubation anneal and its conditions on SPC kinetics and resulting properties of polycrystalline silicon thin-film solar cells are studied. The incubation period at 600 °C can be shortened by 50–80% (by 200–400 min) and the crystal growth rate can be doubled after only a few minute long enhanced-incubation anneal at 640 or 680 °C. However, cell performance parameters degrade for all such pre-treatments in a direct correlation with treatment intensity: the higher enhanced-incubation temperature and the longer its time, the worse the cell performance. Both open circuit voltage and short circuit current gradually decrease with longer and hotter enhanced-incubation annealing. It is the cell Blue Response that is mostly affected by the treatment, while the red Response stays similar. Accordingly, the modeled minority carrier diffusion length is shorter in the cell emitter and it does not change in the absorber after the enhanced-incubation anneal. The increasing diode ideality factor means more depletion region recombination, which also indicates that the applied treatment predominantly affects the front, glass-side layers of the cell, where the junction and the emitter are located. The observed results are unexpected as the cell performance worsens for treatments conducted within the incubation period only, i.e. before nucleation and crystal growth start to take place and the Si film is still fully amorphous. The results draw attention to the importance of the incubation period to the final electronic quality of the polycrystalline Si.
-
structural electrical and photovoltaic characterization of si nanocrystals embedded sic matrix and si nanocrystals c si heterojunction devices
Solar Energy Materials and Solar Cells, 2008Co-Authors: Dengyuan Song, Eunchel Cho, Gavin Conibeer, Chris Flynn, Yidan Huang, Martin A GreenAbstract:Abstract Thin films of Si nanocrystals (Si NCs) embedded in a silicon carbide (SiC) matrix (Si-NC:SiC) were prepared by alternating deposition of Si-rich silicon carbide (Si1−xCx) and near-stoichiometric SiC mutilayers (Si1−xCx/SiC) using magnetron cosputtering followed by a post-deposition anneal. Transmission electron microscopy and Raman spectroscopy revealed that the Si NCs were clearly established, with sizes in the range of 3–5 nm. Optical studies showed an increase in the optical band gap after annealing from ∼1.4 eV (as-deposited) to ∼2.0 eV (annealed at 1100 °C). P-type Si-NC:SiC/n-type crystalline silicon (c-Si) heterojunction (HJ) devices were fabricated and their electrical and photovoltaic properties were characterized. The diode showed a good rectification ratio of 1.0×104 at the bias voltage of ±1.0 V at 298 K. The diode ideality factor and junction built-in potential deduced from current–voltage and capacitance–voltage plots are ∼1.24 and 0.72 V, respectively. Illuminated I–V properties showed that the 1-sun open-circuit voltage, short-circuit current density and fill factor of a typical HJ solar cell were 463 mV, 19 mA/cm2 and 53%, respectively. The external quantum efficiency and internal quantum efficiency showed a higher Blue Response than that of a conventional c-Si homojunction solar cell. Factors limiting the cell's performance are discussed.
Sihua Zhong - One of the best experts on this subject based on the ideXlab platform.
-
black silicon on emitter diminishes the lateral electric field and enhances the Blue Response of a solar cell by optimizing depletion region uniformity
Scripta Materialia, 2013Co-Authors: Zenan Shen, Bangwu Liu, Yang Xia, Jie Liu, Jinhu Liu, Sihua ZhongAbstract:A black silicon on emitter (BSOE) solar cell, with a uniform depletion region, was investigated by its internal quantum efficiency (IQE) and by scanning electron microscopy using an electron beam-induced current. We establish a three-dimensional energy band diagram of a non-uniform depletion region to illustrate the shunt effect by introducing a lateral electric field into the black silicon solar cell. The IQE spectral Response at 450 nm is enhanced by ∼31%. The conversion efficiency is improved by 0.8%abs compared with a black silicon solar cell.
Hao-chih Yuan - One of the best experts on this subject based on the ideXlab platform.
-
multi scale surface texture to improve Blue Response of nanoporous black silicon solar cells
Applied Physics Letters, 2011Co-Authors: Fatima Toor, Howard M. Branz, Matthew Page, K M Jones, Hao-chih YuanAbstract:We characterize the optical and carrier-collection physics of multi-scale textured p-type black Si solar cells with conversion efficiency of 17.1%. The multi-scale texture is achieved by combining density-graded nanoporous layer made by metal-assisted etching with micron-scale pyramid texture. We found that (1) reducing the thickness of nanostructured Si layer improves the short-wavelength spectral Response and (2) multi-scale texture permits thinning of the nanostructured layer while maintaining low surface reflection. We have reduced the nanostructured layer thickness by 60% while retaining a solar-spectrum-averaged black Si reflectance of less than 2%. Spectral Response at 450 nm has improved from 57% to 71%.
Zenan Shen - One of the best experts on this subject based on the ideXlab platform.
-
black silicon on emitter diminishes the lateral electric field and enhances the Blue Response of a solar cell by optimizing depletion region uniformity
Scripta Materialia, 2013Co-Authors: Zenan Shen, Bangwu Liu, Yang Xia, Jie Liu, Jinhu Liu, Sihua ZhongAbstract:A black silicon on emitter (BSOE) solar cell, with a uniform depletion region, was investigated by its internal quantum efficiency (IQE) and by scanning electron microscopy using an electron beam-induced current. We establish a three-dimensional energy band diagram of a non-uniform depletion region to illustrate the shunt effect by introducing a lateral electric field into the black silicon solar cell. The IQE spectral Response at 450 nm is enhanced by ∼31%. The conversion efficiency is improved by 0.8%abs compared with a black silicon solar cell.
Miro Zeman - One of the best experts on this subject based on the ideXlab platform.
-
determination of defect density of state distribution of amorphous silicon solar cells by temperature derivative capacitance frequency measurement
Journal of Applied Physics, 2014Co-Authors: Guangtao Yang, R A C M M Van Swaaij, S Dobrovolskiy, Miro ZemanAbstract:In this contribution, we demonstrate the application temperature dependent capacitance-frequency measurements (C-f) to n-i-p hydrogenated amorphous silicon (a-Si:H) solar cells that are forward-biased. By using a forward bias, the C-f measurement can detect the density of defect states in a particular energy range of the interface region. For this contribution, we have carried out this measurement method on n-i-p a-Si:H solar cells of which the intrinsic layer has been exposed to a H2-plasma before p-type layer deposition. After this treatment, the open-circuit voltage and fill factor increased significantly, as well as the Blue Response of the solar cells as is concluded from external quantum efficiency. For single junction, n-i-p a-Si:H solar cells initial efficiency increased from 6.34% to 8.41%. This performance enhancement is believed to be mainly due to a reduction of the defect density in the i-p interface region after the H2-plasma treatment. These results are confirmed by the C-f measurements. Af...