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Dark current–voltage and photovoltaic characteristics for the flat Si and etched Si solar cell. (a) The dark current–voltage characteristics for the flat Si and etched Si solar cell. (b) The photovoltaic characteristics for the flat Si and etched Si solar cell. The etching time ranged from 0.5 to 15 min.
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In this study, we applied a metal catalyst etching method to fabricate a nano/microhole array on a Si substrate for application in solar cells. In addition, the surface of an undesigned area was etched because of the attachment of metal nanoparticles that is dissociated in a solution. The nano/microhole array exhibited low specular reflectance (<1%...
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An investigation was conducted into the process of microscale hole drilling, in which commercially available uncoated and TiAlN coated WC/Co drill bits were used for microhole drilling in the Ni-based superalloy Inconel X-750. The life of the drill bits, quality of holes drilled, and the mode of drill bit damage during the machining process were ev...
Citations
... Electrochemical etching will increase the dark 49 current of the device, and the size of pores is difficult to 50 control. The micro-hole array structure is also a feasible 51 method, which has been applied in solar cells to improve light 52 absorption [19], [20]. 53 In this work, 4H-SiC p-i-n UV PDs with periodic micro-54 hole arrays are fabricated. ...
... Electrochemical etching will increase the dark 49 current of the device, and the size of pores is difficult to 50 control. The micro-hole array structure is also a feasible 51 method, which has been applied in solar cells to improve light 52 absorption [19], [20]. ...
In this report, 4H-SiC p-i-n photodiodes with various micro-hole arrays are fabricated, then measured and discussed by using photoelectric measurement system and simulation software. Periodic micro-hole arrays etched from p layer to i layer are obtained by using the selective etching technology, which increases the photosensitive area of devices and reduces the ultraviolet light absorption of p layer. The average dark current of devices has an ultralow value of approximate 6.0×10-15 A in the low reverse bias range of 0-10 V. Furthermore, the device with 4 μm micro-hole exhibits the best performance and its peak responsivity increased by 10.4 % compared to the conventional device. It is significant that the peak responsivity and corresponding external quantum efficiency of devices with 4 μm micro-hole at 40 V bias are 815 % and 819 % higher than those of devices without micro-hole, respectively. This is attribute to the fact that a high electric field is observed around the micro-holes as the reverse bias increased to 40 V, which leads to local avalanche. Thus, the local avalanche photodiodes work at a relatively low bias, which improved the responsivity and quantum efficiency of the device enormously.
... The lower PR intensities in the nanotextured sample compared with those of the microtextured reference sample indicate the light-absorption enhancement of the nanoporous structure [37]. From the SEM images and the PR spectra, the nanoporous surface of the sample with the etching time of 10 sec shows a light absorption that is an improvement over the samples with the times of 30 and 60 sec, which indicates an overetching effect on the light-absorption reduction. ...
We investigated superhydrophobic Si nanosurfaces similar to the lotus leaf by performing a hierarchical nanotexturing process on micropyramidal Si surfaces. The process was carried out using a metal-assisted chemical etching process based upon the deposition of Ag nanoparticles. The hierarchical micro-nanosurfaces showed a superhydrophobic character with contact angles of approximately 134∼150°. The photon tunnelling also provides a strong light absorption as a black Si. The surface-light emission from broad and sharp photoluminescence was observed in the wavelength ranges of 414.7∼440 and 509∼516.2 nm. The field-induced tunnelling current on nanosurface shows the formation of quantum surface states. From the analyses of Casimir-Lifshitz quantum state of a photon in vacuum, the superhydrophobic behaviour of water droplet is closely related to the nanosurface and the nanoporous cavity shows the absorption of terahertz energy. Si nanosurface shows the broadband absorption in the spectral range of 800∼900 cm⁻¹ corresponding to the energy range of 99.2∼111.6 meV with 24∼27 THz.
... The cross-sectional SEM after TiO 2 deposition (lower right) indicated that the TiO 2 fully covered the Si nanostructure with an uneven surface. 28 Because of its ability to provide full coverage, the LPD-TiO 2 could be used as a liner for the proposed conducting polymer deposition and form a Schottky contact in a solar cell. The spin-coated PEDOT:PSS could effectively penetrate into the Si nanohole, because TiO 2 can alter the Si surface from being hydrophobic to hydrophilic. ...
We demonstrated a high performance Si-organic hybrid heterojunction solar cell utilizing low temperature and liquid phase-processed TiO2 as an interlayer between PEDOT:PSS and Si nanoholes to produce a conformal contact on the surface of the Si nanostructure. The hydrophilic TiO2/Si-nanohole surface enabling the PEDOT:PSS to flow into the spacing of the close-packed nanoholes. SEM images were used to confirm the PEDOT:PSS nanohole filling induced by the TiO2. With forming gas annealing of the double-sided TiO2, high Voc (0.63 V) and Jsc (35.7 mA/cm2) were obtained, yielding a high power conversion efficiency of 14.7%. The high Voc was attributed to the surface passivation of Si by annealed TiO2. The XPS investigation at the TiO2/Si interface indicates the TiOx signal decreased and the TiO2 and SiOx signals increased after annealing. The Si–O bonding found in the O1s study appeared in the form of Si–O–Si bonding to serve surface passivation. The band alignment of the PEDOT:PSS/TiO2/n-Si hetero-interfaces was postulated and plotted. The Vbi in the system after annealing was assumed to be higher because of the reduction of bulk and surface states that yield high Voc. After annealing, the Vbi increased from 0.805 to 0.905 V. The reduction of surface recombination velocity proved the passivation ability of TiO2 after annealing. With proven surface passivation and conformal PEDOT:PSS/Si nanohole interfaces for enhanced contact, this Si-organic hybrid heterojunction solar cell with solution-processed TiO2 interlayers has excellent potential for application as a high-efficiency and low-cost Si solar cell.
