Polarization-induced hole doping for long-wavelength In-rich InGaN solar cells

2021 ◽  
Vol 119 (20) ◽  
pp. 202103
Author(s):  
Liwen Sang ◽  
Masatomo Sumiya ◽  
Meiyong Liao ◽  
Yasuo Koide ◽  
Xuelin Yang ◽  
...  
Keyword(s):  
Solar Cells ◽  
Hole Doping ◽  
Long Wavelength

Evaluation of Ar-Diluted Silane PECVD for Thin Film Si:H Based Solar Cells

2004 ◽  
Vol 808 ◽  
Author(s):  
J. A. Anna Selvan ◽  
Yuan-Min Li ◽  
Liwei Li ◽  
Alan E. Delahoy
Keyword(s):  
Solar Cells ◽  
Spectral Response ◽  
Nanocrystalline Silicon ◽  
Thin Layers ◽  
Dilution Method ◽  
Critical Question ◽  
Long Wavelength ◽  
Hydrogen Dilution ◽  
Porous Microstructure ◽  
The Stability

ABSTRACTDilution by Ar of silane plasma has been reported to increase the stability of a-Si:H films. A critical question is whether Ar diluted i-layers offer higher stabilized solar cell efficiencies than the conventional hydrogen dilution method. We have fabricated a-Si:H p-i-n solar cells with RF-PECVD i-layers by Ar dilution of silane. Ar dilution ratio (ADR, Ar/SiH4), RF power,pressure, and i-layer thickness were varied. At low ADR < 20, such solar cells show comparable initial efficiencies and stability as those devices having H2-diluted i-layers of similar thickness. For cells made with ADR > 20, the initial efficiency decreases dramatically with further increase in Ar dilution, and light soaking causes only mild changes in efficiencies. The stabilized efficiencies of cells made with high ADR are inferior to the cells produced with low ADR or cells prepared by H2 dilution. Further, Voc of solar cells made with high ADR (> 50) decreases substantially in ambient, indicating a porous microstructure susceptible to oxidation. While thermal annealing improves the Voc, a full recovery of Voc is made by accelerated light soaking.The combination of high power and high ADR can lead to nanocrystalline silicon (nc-Si:H) growth, although nucleation is much more difficult to attain by the Ar dilution method compared to hydrogen dilution. We have succeeded in fabricating p-i-n solar cells with nc-Si:H i-layers prepared by the Ar dilution approach. The double dilution by Ar and hydrogen of silane (Ar+H2+SiH4) can result in nc-Si:H i-layers with enhanced long wavelength spectral response compared to devices incorporating nc-Si:H i-layers grown by H2 dilution only. The nc-Si:H solar cells with Ar+H2 diluted i-layers exhibit no light-induced degradation.Using energetic Ar-rich plasma, in a process much simpler than the traditional nc-Si:H technique, doped a-Si:H thin layers can be prepared to form excellent tunnel junctions for multi-junction solar cells. We demonstrate such a novel, non-contaminating tunnel junction in tandem a-Si/a-Si and a-Si/nc-Si solar cells entirely fabricated in a single-chamber RF-PECVD system.

Mechanism of the Improvement in Microcrystalline Silicon Solar Cells by Hydrogen Plasma Treatment

2013 ◽  
Vol 773 ◽  
pp. 118-123
Author(s):  
Jing Yan Li ◽  
Xiang Bo Zeng ◽  
Hao Li ◽  
Xiao Bing Xie ◽  
Ping Yang ◽  
...  
Keyword(s):  
Solar Cells ◽  
Electric Field ◽  
Plasma Treatment ◽  
Defect Density ◽  
Hydrogen Plasma ◽  
Microcrystalline Silicon ◽  
One Dimensional ◽  
Long Wavelength ◽  
Drift Length ◽  
Experimental Improvement

We explain the experimental improvement in long wavelength response by hydrogen plasma treatment (HPT) in n/i interface. The absorption coefficient of the intrinsic microcrystalline silicon (μc-Si) is decreased in the low energy region (0.8~1.0 eV) by HPT, which indicates a lower defect density in μc-Si layer deposited with HPT than its counterpart without HPT. Simulation by one-dimensional device simulation program for the Analysis of Microelectronic and Photonic Structures (AMPS-1D) shows a higher long wavelength response in μc-Si solar cell if the defect density in intrinsic μc-Si layer is smaller. Our simulation results also disclose that the less defect density in intrinsic layer, the lower recombination rate and the higher electric field is. Higher electric field results in longer drift length which will promote collection of carriers generated by photons with long wavelength. Thus we deduce that HPT decreased defect density in absorber layer and improved the performance of μc-Si solar cells in long wavelength response.

scholarly journals GINZBURG–LANDAU LIKE THEORY OF HIGH TEMPERATURE SUPERCONDUCTIVITY IN THE CUPRATES: EMERGENT d-WAVE ORDER

2012 ◽  
Vol 26 (10) ◽  
pp. 1230005
Author(s):  
T. V. RAMAKRISHNAN
Keyword(s):  
High Temperature ◽  
Cooper Pair ◽  
Nearest Neighbor ◽  
High Temperature Superconductivity ◽  
Transition Curve ◽  
Hole Doping ◽  
Positive Interaction ◽  
Long Wavelength ◽  
Spin Singlet ◽  
D Wave

High temperature superconductivity in the cuprates remains one of the most widely investigated, constantly surprising and poorly understood phenomena in physics. Here, we describe briefly a new phenomenological theory inspired by the celebrated description of superconductivity due to Ginzburg and Landau and believed to describe its essence. This posits a free energy functional for the superconductor in terms of a complex order parameter characterizing it. We propose that there is, for superconducting cuprates, a similar functional of the complex, in plane, nearest neighbor spin singlet bond (or Cooper) pair amplitude ψij. Further, we suggest that a crucial part of it is a (short range) positive interaction between nearest neighbor bond pairs, of strength J′. Such an interaction leads to nonzero long wavelength phase stiffness or superconductive long range order, with the observed d-wave symmetry, below a temperature Tc~z J′ where z is the number of nearest neighbors; d-wave superconductivity is thus an emergent, collective consequence. Using the functional, we calculate a large range of properties, e.g., the pseudogap transition temperature T* as a function of hole doping x, the transition curve Tc(x), the superfluid stiffness ρs(x, T), the specific heat (without and with a magnetic field) due to the fluctuating pair degrees of freedom and the zero temperature vortex structure. We find remarkable agreement with experiment. We also calculate the self-energy of electrons hopping on the square cuprate lattice and coupled to electrons of nearly opposite momenta via inevitable long wavelength Cooper pair fluctuations formed of these electrons. The ensuing results for electron spectral density are successfully compared with recent experimental results for angle resolved photo emission spectroscopy (ARPES), and comprehensively explain strange features such as temperature dependent Fermi arcs above Tc and the "bending" of the superconducting gap below Tc.

Light-trapping in Thin Film Silicon Solar Cells with a Combination of Periodic and Randomly Textured Back-reflectors

2012 ◽  
Vol 1426 ◽  
pp. 117-123 ◽  
Author(s):  
Sambit Pattnaik ◽  
Nayan Chakravarty ◽  
Rana Biswas ◽  
D. Slafer ◽  
Vikram Dalal
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Light Absorption ◽  
Nanoimprint Lithography ◽  
Light Trapping ◽  
Silicon Solar Cells ◽  
Long Wavelength ◽  
Thin Film Silicon ◽  
Back Reflectors ◽  
Back Reflector

ABSTRACTLight trapping is essential to harvest long wavelength red and near-infrared photons in thin film silicon solar cells. Traditionally light trapping has been achieved with a randomly roughened Ag/ZnO back reflector, which scatters incoming light uniformly through all angles, and enhances currents and cell efficiencies over a flat back reflector. A new approach using periodically textured photonic-plasmonic arrays has been recently shown to be very promising for harvesting long wavelength photons, through diffraction of light and plasmonic light concentration. Here we investigate the combination of these two approaches of random scattering and plasmonic effects to increase cell performance even further. An array of periodic conical back reflectors was fabricated by nanoimprint lithography and coated with Ag. These back reflectors were systematically annealed to generate different amounts of random texture, at smaller spatial scales, superimposed on a larger scale periodic texture. nc-Si solar cells were grown on flat, periodic photonic-plasmonic substrates, and randomly roughened photonic-plasmonic substrates. There were large improvements (>20%) in the current and light absorption of the photonic-plasmonic substrates relative to flat. The additional random features introduced on the photonic-plasmonic substrates did not improve the current and light absorption further, over a large range of randomization features.

scholarly journals Optimization ofμc-Si1−xGex:H Single-Junction Solar Cells with Enhanced Spectral Response and Improved Film Quality

2015 ◽  
Vol 2015 ◽  
pp. 1-9
Author(s):  
Yen-Tang Huang ◽  
Pei-Ling Chen ◽  
Po-Wei Chen ◽  
Hung-Jung Hsu ◽  
Cheng-Hang Hsu ◽  
...  
Keyword(s):  
Solar Cells ◽  
Spectral Response ◽  
Rf Power ◽  
Single Junction ◽  
Long Wavelength ◽  
Tandem Cell ◽  
Cell Efficiency ◽  
Photo Conductivity ◽  
Gas Ratio ◽  
Incorporation Efficiency

Effects of RF power on optical, electrical, and structural properties ofμc-Si1−xGex:H films was reported. Raman and FTIR spectra fromμc-Si1−xGex:H films reflected the variation in microstructure and bonding configuration. Unlike increasing the germane concentration for Ge incorporation, low RF power enhanced Ge incorporation efficiency inμc-Si1−xGex:H alloy. By decreasing RF power from 100 to 50 W at a fixed reactant gas ratio, the optical bandgap ofμc-Si1−xGex:H was reduced owing to the increase in Ge content from 11.2 to 23.8 at.%, while Ge-related defects and amorphous phase were increased. Consequently, photo conductivity of 1.62 × 10−5 S/cm was obtained for theμc-Si1−xGex:H film deposited at 60 W. By applying 0.9 μm thickμc-Si1−xGex:H absorber withXCof 48% and [Ge] of 16.4 at.% in the single-junction cell, efficiency of 6.18% was obtained. The long-wavelength response ofμc-Si1−xGex:H cell was significantly enhanced compared with theμc-Si:H cell. In the case of tandem cells, 0.24 μm a-Si:H/0.9 μmμc-Si1−xGex:H tandem cell exhibited a comparable spectral response as 0.24 μm a-Si:H/1.4 μmμc-Si:H tandem cell and achieved an efficiency of 9.44%.

scholarly journals Development of Hydrogenated Microcrystalline Silicon-Germanium Alloys for Improving Long-Wavelength Absorption in Si-Based Thin-Film Solar Cells

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Yen-Tang Huang ◽  
Hung-Jung Hsu ◽  
Shin-Wei Liang ◽  
Cheng-Hang Hsu ◽  
Chuang-Chuang Tsai
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Silicon Germanium ◽  
Volume Fraction ◽  
Thin Film Solar Cells ◽  
Crystalline Volume Fraction ◽  
Microcrystalline Silicon ◽  
Single Junction ◽  
Long Wavelength ◽  
Wavelength Absorption

Hydrogenated microcrystalline silicon-germanium (μc-Si1-xGex:H) alloys were developed for application in Si-based thin-film solar cells. The effects of thegermane concentration(RGeH4)and thehydrogen ratio(RH2)on theμc-Si1-xGex:H alloys and the corresponding single-junction thin-film solar cells were studied. The behaviors of Ge incorporation in a-Si1-xGex:H andμc-Si1-xGex:H were also compared. Similar to a-Si1-xGex:H, the preferential Ge incorporation was observed inμc-Si1-xGex:H. Moreover, a higherRH2significantly promoted Ge incorporation for a-Si1-xGex:H, while the Ge content was not affected byRH2inμc-Si1-xGex:H growth. Furthermore, to eliminate the crystallization effect, the 0.9 μm thick absorbers with a similar crystalline volume fraction were applied. With the increasingRGeH4, the accompanied increase in Ge content ofμc-Si1-xGex:H narrowed the bandgap and markedly enhanced the long-wavelength absorption. However, the bias-dependent EQE measurement revealed that too much Ge incorporation in absorber deteriorated carrier collection and cell performance. With the optimization ofRH2andRGeH4, the single-junctionμc-Si1-xGex:H cell achieved an efficiency of 5.48%, corresponding to the crystalline volume fraction of 50.5% and Ge content of 13.2 at.%. Compared toμc-Si:H cell, the external quantum efficiency at 800 nm had a relative increase by 33.1%.

Voltage Enhancement in Quasi-Solid-State Dye-Sensitized Solar Cells Using Long Wavelength Absorbing Unsymmetrical Squaraine Dye

2016 ◽  
Vol 8 (12) ◽  
pp. 2183-2188
Author(s):  
Suresh Thogiti ◽  
Chi Hwan Lee ◽  
Weon Ki Yang ◽  
Hyeong Jin Yun ◽  
Jae Hong Kim
Keyword(s):  
Solar Cells ◽  
Solid State ◽  
Dye Sensitized Solar Cells ◽  
Long Wavelength ◽  
Dye Sensitized ◽  
Squaraine Dye ◽  
Sensitized Solar Cells
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