P-type Monocrystalline Silicon Wafer Research Articles

A Micro Capacitive Humidity Sensor Based on Al-Mo Electrodes and Polyimide Film.

Quickly sensing humidity changes is required in some fields, such as in fuel cell vehicles. The micro humidity sensor used for the relative humidity (RH) measurement with fast response characteristics, and its numerical model and method are rare. This paper firstly presents a numerical model and method for a parallel plate capacitor and a numerical analysis of its dynamic characteristics. The fabrication of this sensor was carried out based on the numerical results, and, the main characteristics of its moisture-sensitive element are shown. This parallel plate capacitor is made using complementary metal-oxide semiconductor (CMOS)-compatible technology, with a P-type monocrystalline silicon wafer used as the substrate, a thin polyimide film (PI) between the upper grid electrode and the lower parallel plate electrode, and electrodes with a molybdenum-aluminum bilayer structure. The shape of the micro sensor is square with 3 mm on the side of the source field. The humidity sensor has a linearity of 0.9965, hysteresis at 7.408% RH, and a sensitivity of 0.4264 pF/%RH. The sensor displays an average adsorption time of 1 s and a minimum adsorption time of 850 ms when the relative humidity increases from 33.2% RH to 75.8% RH. The sensor demonstrates very good stability during a 240 h test in a 25 °C environment. The numerical model and method provided by this study are very useful for predicting the performance of a parallel plate capacitor.

Study of the Enhanced Efficiency of Crystalline Silicon Solar Cells by Optimizing Anti Reflecting Coating using PC1D Simulation

In this paper, simulation of a mono crystalline silicon solar cell was done using PC1D software. The impact of different solar cell parameters, with their effects on power and efficiency, has been investigated. It is seen that the textured surface reduces reflection and increases the efficiency of the solar cell at least 2–3%. From the simulation, it is seen that the optimum value of p-type doping concentration 1 × 10^16 cm^−3, n-type doping concentration 5 × 10^18 cm with pyramid height of 2–3 μm and equal angles of 54.74 degrees produces the best result in simulation. An anti-reflective coating with a refractive index of 1.38 and a thickness of 84 nm is considered optimal. By optimizing the effective parameters, a solar cell with an efficiency of 24.45% was achieved through simulation. For a p-type mono crystalline silicon wafer, with an area of 10 × 10 cm^2 and a thickness of 200 μm, initial simulation shows a 24.45% efficient solar cell.

Fabrication of N-Type Nanocrystalline Silicon Thin-Film by Magnetron Sputtering and Antimony Induced Crystallization

The fabrication of n-type nanocrystalline silicon thin films using magnetron sputtering and crystallization by adding antimony and thermal treatment is presented in this article. Firstly, a short overview about thin film deposition methods, along with the advantages and disadvantages of the magnetron sputtering, is provided. Then, the technique of adding metals for recrystallization of amorphous silicon is described, and the necessity of using antimony for obtaining n-type nanocrystalline silicon along with its characteristics is discussed. Next, the process of thin film deposition using magnetron sputtering and the production of n-type nanocrystalline silicon on a quartz substrate, by antimony induced crystallization, is explained. Subsequently, the characterization process and necessary measurements to confirm the crystallization of the nanocrystalline silicon layer and determine its crystalline properties are presented. For ease of electrical characterization, a simple n/p junction Schottky solar cell is fabricated using the produced nanocrystalline silicon layer on a p-type monocrystalline silicon wafer. In addition to nanocrystalline properties, the optical and electrical characteristics of this cell are also investigated. The measurements show that with the proposed method, a fine grains nanocrystalline silicon layer with an average grain size of 20 nm was formed in the <111> direction. J-V characteristic measurement shows the creation of a solar cell with conversion efficiency of 1.39%, open circuit voltage of 265mV and current density of 16.32mA/cm2. These results confirm that antimony can be used in the process of crystallizing amorphous thin film silicon obtained from magnetron sputtering and converting it into n-type nanocrystalline silicon.

Synthesis, Crystal Structures, and Nonlinear Optical Properties of Chalcone Doped by Titanium Dioxide Nanoparticles for Solar Cell Application

In this work, we investigate the effects of titanium dioxide (TiO2) nanoparticle percentages on the optical and electrical properties of 3-(4-(dimethyl-amino)phenyl)-1-phenyl-(2E)-propen-1-one (DAAP). In order to achieve thin films, DAAP was dissolved in acetone and doped with different ratios of TiO2. The pure and composite mixtures were spin-coated onto a glass substrate. We investigated the influence of TiO2 on XRD patterns, absorption, energy band gaps, refractive indices, sheet resistance, resistivity, and Hall coefficients. We used the XRD technique to study the structure of DAAP pre- and post-doping with TiO2 nanoparticles. It was evident from the XRD patterns that the composite transformed from an amorphous to a polycrystalline nature and behaved similarly to titanium oxide crystals. The pure sample exhibited an absorption band of 409 nm. With the addition of TiO2, the whole absorption spectrum shifted to the blue region. For example, with a dopant percentage of 15%, the spectrum shifted to a wavelength of 368 nm. The energy band gap values increased with a dopant concentration from 2.65 eV of pure DAAP to 2.91 eV of maximum dopant percentage (15%). The refractive index decreased to its lowest value of 2.47 with the increase in TiO2 concentration. The impact of increasing TiO2 percentage highly improved electrical characteristics by reducing the sheet resistance and resistivity to 905 k(Ω/sq) and 230 k on the (Ω · cm), respectively. An optimized DAAP doped with 15% TiO2 has been used as an n-type layer on a p-type monocrystalline silicon wafer (Si (111)) to fabricate η = 0.23% efficient solar cells. On the other hand, the amplified spontaneous emission (ASE) of the DAAP and dopant mixture was excited by the third harmonic generation (λex = 355 nm). The pure DAAP exhibits an ASE peak at 535 nm. The intensity decreased rapidly with increased dopant concentration, whereas the full width at half-maximum (FWHM) increased slightly.

Preparation and Spectrial Studies of Silicon Nitride Thin Films Containing Amorphous Silicon Quantum Dots

Silicon-rich silicon nitride thin films are prepared on P-type monocrystalline silicon wafer (100) and glass substrate by plasma chemical vapor deposition with reaction gas sources SiH4 and NH3. The deposited samples are thermally annealed from 600°C to 1000°C in an atmosphere furnace filled with high purity nitrogen. The annealing time is 60 minutes. Fourier transform infrared spectroscopy (FTIR) is carried out to investigate the bonding configurations in the films. The results show that the Si-H bond and N-H bond decrease with the increase of annealing temperature, and completely disappear at the annealing temperature of 900°C. But the Si-N bond is enhanced with the increase of annealing temperature, and the blue shift occurs, then Si content in the film increases. The Raman Spectra show that the amorphous Si Raman peak appears at 480 cm-1 in the film at 700°C. The Raman spectra of the films annealed at 1000 °C is fitted with two peaks, and a peak at 497 cm -1 is found, which indicated that the Si phase in the films changed from amorphous to crystalline with the increase of annealing temperature. The experiment also analyses the luminescence properties of the samples through PL spectrum, and it is found that there are five luminescence peaks in each sample under different annealing temperature. Based on the analysis of Raman spectrum and FTIR spectrum, the PL peak of amorphous silicon quantum dots appears at the wavelength range of 525-555nm, and the other four PL peaks are all from the defect state luminescence in the thin films, and the amorphous silicon quantum dot size is calculated according to the formula.

Geometrical optimisation of core-shell nanowire arrays for enhanced absorption in thin crystalline silicon heterojunction solar cells.

Background: Elongated nanostructures, such as nanowires, have attracted significant attention for application in silicon-based solar cells. The high aspect ratio and characteristic radial junction configuration can lead to higher device performance, by increasing light absorption and, at the same time, improving the collection efficiency of photo-generated charge carriers. This work investigates the performance of ultra-thin solar cells characterised by nanowire arrays on a crystalline silicon bulk.Results: Proof-of-concept devices on a p-type mono-crystalline silicon wafer were manufactured and compared to flat references, showing improved absorption of light, while the final 11.8% (best-device) efficiency was hindered by sub-optimal passivation of the nanowire array. A modelling analysis of the optical performance of the proposed solar cell architecture was also carried out. Results showed that nanowires act as resonators, amplifying interference resonances and exciting additional wave-guided modes. The optimisation of the array geometrical dimensions highlighted a strong dependence of absorption on the nanowire cross section, a weaker effect of the nanowire height and good resilience for angles of incidence of light up to 60°.Conclusion: The presence of a nanowire array increases the optical performance of ultra-thin crystalline silicon solar cells in a wide range of illumination conditions, by exciting resonances inside the absorber layer. However, passivation of nanowires is critical to further improve the efficiency of such devices.

Band gap Measurement of P – type Monocrystalline Silicon Wafer

Band gap of P-type monocrystalline silicon wafer has been measured using spectral response measurement system. To see the spectral response a SR510 lock in amplifier, SR540 optical chopper, monochromator (400nm-1200nm), optical detector and lab view software has been used. From spectral response of polished P-type monocrystalline silicon wafer absorption, reflection and transmission has been respectively seen from 400nm-550nm, 550nm-1050nm and 1050-1200nm. Assuming band gap of silicon is (1.12eV), this result has been theoretically verified using Planck–Einstein relation. Moreover, theoretical band gap of silicon has been calculated (1.127362 eV). The band gap measurement process uses partial concept of Tauc’s downhill negative slop and Planck–Einstein relation. Experimental result shows that, the band gap of silicon is 1.127907 eV.Bangladesh J. Sci. Ind. Res.53(3), 179-184, 2018

Study of the Enhancement of the Efficiency of the Monocrystalline Silicon Solar Cell by Optimizing Effective Parameters Using PC1D Simulation

In this paper, simulation of a monocrystalline silicon solar cell was done using PC1D software. The impact of different solar cell parameters, with their effects on power and efficiency, has been investigated. For a p-type monocrystalline silicon wafer, with an area of $10\times 10$ cm2 and a thickness of 300 μm, initial simulation shows a 12.10% efficient solar cell. To optimize the simulation experimentally obtained data has been used in the texturization process. It is seen that the textured surface reduces reflection and increases the efficiency of the solar cell at least 1–2%. From the simulation it is seen that the optimum value of p-type doping concentration is $1\times 10^{17}$ cm− 3 and n-type doping concentration is $1\times 10^{18}$ cm− 3. 200.3 μm diffusion length is considered as optimum. Both sides textured wafer with pyramid height of 2–3 $\mu \mathrm {m}$ and equal angles of 54.74 degrees produces the best result in simulation. An anti-reflection coating with 2.019 refractive index and a thickness of 74 nm is considered as optimum. By optimizing the effective parameters, a 20.35% efficient solar cell has been achieved by simulation.

Electrochemical synthesis and the gas-sensing properties of the Cu2O nanofilms/porous silicon hybrid structure

A novel composite of Cu2O nanofilms/porous silicon hybrid structure has been successfully synthesized using porous silicon as growth substrate by electrochemical synthesis. Orderly porous silicon (PS) substrate with the aperture about 1.5μm and hole depth about 10μm was prepared by electrochemical etching of a p-type monocrystalline silicon wafer in a double-tank cell. The Cu2O nanofilms have been grown onto PS substrates by electrochemical deposition with different electrodeposition time. The obtained Cu2O nanofilms/PS products were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM). The gas-sensing properties of Cu2O nanofilms/PS composites to NO2 were studied by the gas-sensing test system. The result indicates that the electrodeposition time has a significant impact on the microstructure and gas-sensing properties of Cu2O nanofilms/PS composites. Due to the high specific surface area and special microstructure, the Cu2O nanofilms/PS gas sensor with the eletrodeposition time of 30min showed good gas-sensing properties to NO2 with a high gas response, fast response–recovery characteristic, excellent repeatability and good selectivity at a working temperature of 175°C. At the working temperature, the gas sensor has a gas response of about 4.5–1ppm NO2. The related gas-sensing mechanism will be discussed.

PC2D simulation and optimization of the selective emitter solar cells fabricated by screen printing phosphoric paste method

On the basis of perfect PC2D simulation to the measured current density vs voltage (J–V) curve of the best selective emitter (SE) solar cell fabricated by the CSG Company using the screen printing phosphoric paste method, we systematically investigated the effect of the parameters of gridline, base, selective emitter, back surface field (BSF) layer and surface recombination rate on performance of the SE solar cell. Among these parameters, we identified that the base minority carrier lifetime, the front and back surface recombination rate and the ratio of the sheet-resistance of heavily and lightly doped region are the four largest efficiency-affecting factors. If all the parameters have ideal values, the SE solar cell fabricated on a p-type monocrystalline silicon wafer can even obtain the efficiency of 20.45%. In addition, the simulation also shows that fine gridline combining dense gridline and increasing bus bar number while keeping the lower area ratio can offer the other ways to improve the efficiency.

Preparation and gas-sensing properties of the silver nanoparticles/porous silicon composite

The p-type porous silicon layer with the aperture about 1.5 microns and hole depth about 15-20 microns is prepared by electrochemical etching of a p-type monocrystalline silicon wafer with a resistivity 10-15 Ω·cm and along [100] orientation in a double-tank cell which consists of the electrolyte (volume ratio HF: DMF=1:2). Silver nanoparticles film with different thickness has been deposited on porous silicon by the electroless deposition for different deposition times. Morphology and microstructure of the silver nanoparticles/porous silicon composite are studied by scanning electron microscope and X ray diffracmeter. Result indicates that the silver nanoparticles are uniformly distributed on the surface of porous silicon and the deposition time has an important influence on the morphology of the composite. The gas-sensing properties of the silver nanoparticles/porous silicon composite to NH3 are tested at room temperature by the static volumetric method. Results show that the deposition time has a significant impact on the gas-sensing properties of the silver nanoparticles/porous silicon. In a short deposition time, the composite with an appropriate amount of silver nanoparticles doped on the porous silicon shows good gas-sensing properties to NH3 with high sensitivity, fast response-recovery characteristic due to the high specific surface area and special microstructure. At room temperature, the gas sensor has a sensitivity of about 5.8 to 50 ppm NH3.

Preparation and gas-sensing properties of the silver nanoparticles/porous silicon composite

The p-type porous silicon layer with the aperture about 1.5 microns and hole depth about 15 microns is prepared by electrochemical etching of a p-type monocrystalline silicon wafer with a resistivity 10-15 cm and along [100] orientation in a double-tank cell which consists of the electrolyte (volume ratio HF: DMF=1:2). Silver nanoparticles film with different thickness has been deposited on porous silicon by the electroless deposition for different deposition times. Morphology and microstructure of the silver nanoparticles/porous silicon composite and ere studied by scanning electron microscope and X ray diffracmeter. Result indicates that the silver nanoparticles are uniformly distributed on the surface of porous silicon and the deposition time has an important influence on the morphology of the composite. The gas-sensing properties of the silver nanoparticles/porous silicon composite to NH3 are tested at room temperature by the static volumetric method. Results show that the deposition time has a significant impact on the gas-sensing properties of the silver nanoparticles/porous silicon. In a short deposition time, the composite with an appropriate amount of silver nanoparticles doped on the porous silicon shows good gas-sensing properties to NH3 with high sensitivity, fast response-recovery characteristic due to the high specific surface area and special microstructure. At room temperature, the gas sensor has a sensitivity of about 5.8 to 50 ppm NH3.

Effect of rapid thermal oxidation on structure and photoelectronic properties of silicon oxide in monocrystalline silicon solar cells

This paper concerns the topic of surface passivation properties of rapid thermal oxidation on p-type monocrystalline silicon wafer for use in screen-printed silicon solar cells. It shows that inline thermal oxidation is a very promising alternative to the use of conventional batch type quartz tube furnaces for the surface passivation of industrial phosphorus-diffused emitters. Five minutes was the most favorable holding time for the rapid thermal oxidation growth of the solar cell sample, in which the average carrier lifetime was increased 19.4 μs. The Fourier transform infrared spectrum of the rapid thermal oxidation sample, whose structure was Al/Al-BSF/p-type Si/n-type SiP/SiO2/SiNx/Ag solar cell with an active area of 15.6 cm2, contained an absorption peak at 1085 cm−1, which was associated with the Si–O bonds in silicon oxide. The lowest average reflectance of this sample is 0.87%. Furthermore, for this sample, its average of internal quantum efficiency and conversion efficiency are respectively increased by 8% and 0.23%, compared with the sample without rapid thermal oxidation processing.

Novel selective emitter process using non-acidic etch-back for inline-diffused silicon wafer solar cells

In this work, a novel etch-back approach for the fabrication of a selective emitter (SE) structure is reported for inline-diffused p-type monocrystalline silicon wafer solar cells. The complete SE process, named the ‘SERIS SE’ process, involves screen printing of an etch mask, use of a HF-free etch-back solution and screen-printed metallisation. Both the emitter etch-back and etch-mask dissolution are performed simultaneously in a single processing step, thereby reducing the number of processing steps as compared to other etch-back based SE technologies. For inline-diffused emitter (ILDE) solar cells, the ‘SERIS SE’ process actually requires only one additional processing step, as an emitter etch-back is typically applied to remove the detrimental top layer. An average cell efficiency gain of 0.4% (absolute) is reported for the SE cells fabricated using the single-step SERIS SE process, as compared to etch-back homogeneous-emitter (HE) solar cells. An average batch efficiency of 18.5% is achieved for screen-printed p-type 156 mm pseudo-square Cz mono-Si full-area aluminium back surface field (Al-BSF) SE solar cells. The minimal increase in the number of processing steps, reliance on the robust screen printing process, HF-free non-acidic chemical etch-back and applicability to both tube and inline-diffused emitters make the ‘SERIS SE’ process suitable for industrial application on both mono- and multicrystalline silicon wafers.

Back contacted a-Si:H/c-Si heterostructure solar cells

This paper shows how the amorphous/crystalline silicon technology can be implemented in the interdigitated back contact solar cell design. We have fabricated rear-junction, backside contact cells in which both the emitter and the back contact are formed by amorphous/crystalline silicon heterostructure, and the grid-less textured front surface is passivated by a double layer of amorphous silicon and silicon nitride, which also provides an anti-reflection coating. The entire self-aligned mask and photolithography-free process is performed at temperature below 300°C with the aid of one metallic mask to create the interdigitated pattern. An open circuit voltage of 687mV has been measured on a 0.5Ωcm p-type monocrystalline silicon wafer. On the other hand, several technological aspects that limit the fill factor (50%) and the short circuit current density (32mA/cm2) still need improvement. We show that the uniformity of the deposited amorphous silicon layers is not influenced by the mask-assisted deposition process and that the alignment is feasible. Moreover, this paper investigates the photocurrent limiting factors by one-dimensional modeling and quantum efficiency measurements.

Innovative design of amorphous/crystalline silicon heterojunction solar cell

In this work we show how the heterostructure technology can have a chance in the challenge of interdigitated back contact solar cell. We present an innovative rear junction, backside contact design in which both the emitter and the back surface field are formed by amorphous/crystalline silicon heterostructure, and the grid-less front surface is passivated by a double layer of amorphous silicon and silicon nitride, which also provides a good anti-reflection coating. The technological processes are performed at temperature below 300 °C with the aid of one metallic mask to create the interdigitated pattern. The initials results, on a p-type monocrystalline silicon wafer; are really promising, a V oc of 687 mV has been reached. We show that the uniformity of the deposited amorphous silicon layers is not influenced by the mask-assisted deposition process and that the alignment is feasible. On the other hand several technological aspects that strongly limit the fill factor (50%) and the short circuit current density (30 mA/cm 2) have to be optimized.

Interface recombination in heterojunctions of amorphous and crystalline silicon

Heterojunction solar cells consisting of an n-type a-Si:H(n) emitter and a p-type monocrystalline silicon wafer have been studied with particular emphasis on the role of interface recombination. It is shown that the form of the I– V characteristics and the effective interface recombination velocity depend on the treatment of the Si-wafer prior to the deposition of the amorphous emitter. Numerical simulation suggests that the non-exponential (S-shape) dependence of the I– V curves under illumination arises from a high density of interface states which results in enhanced recombination via interface states.