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In this work, SWCNTm / PLA was employed as a fundamental compound, and nanofilms of SWCNTm / PLA were coated onto n-kind silicon substrates. The spin coated technique was used to determine the thickness in (SWCNTm / PLA). Various thicknesses in (SWCNTm / PLA) (162, 100, and 82) n.m are procured via at vary spin spades (1500, 3000, and 4500) r.pm.' light (100 mw/cm2) and dark (J-V) requirements were used to produce the current denisity-volt features. The characteristics of the photovoltaic models namely, open circuit voltage (Voc), short–circuit current density (Jsc), foll ratio (FF), and energy conversion efficiency (ɳ) were calculated. The better thickness of (SWCNTm / PLA) films for highest (ɳ), (Jsc) and greatest power point presentation' is 100 n m, according to our findings.

The presented experiments and studies are intended for photovoltaic applications of crystalline silicon. This work deals with chemical treatment of the surface of n-type silicon wafers with different resistivity to reduce their reflectivity. Chemical surface treatment of silicon is an alternative method to using the antireflection layer. Optical losses caused by the reflection of light from the surface of the solar cells significantly reduce their efficiency. The investigated samples were prepared by the electrochemical etching method in the solution based on hydrofluoric acid and ethanol. The analysis of the prepared samples is divided into two parts, namely experimental measurements, and theoretical modeling. Experimental measurements are performed using UV-VIS spectroscopy, spectroscopic ellipsometry and SEM microscopy. Theoretical modeling is based on the construction and optimization of theoretical model of optical response (reflectivity and ellipsometric parameters) to determine the effective refractive index and thickness of formed structure. Effective refractive index of studied samples in theoretical model of optical response is based on Looyenga effective medium approximation and Tauc-Lorentz dispersion model.

Bifacial crystalline silicon (c-Si) solar cells have currently attracted much attention due to the front high-efficiency and additional gain of power generation from the back side. Here, we have presented n-type passivated emitter and rear totally-diffused (n-PERT) bifacial c-Si solar cells featuring front selective emitter (SE) and polysilicon (poly-Si) based passivating contacts. The SE formation was scanned with laser doping based on front boron-diffusion p+ emitter. The poly-Si based passivating contacts consisting of nano-layer SiOx of ~1.5 nm thickness grown with cost-effective nitric acid oxidation and phosphorus-doped polysilicon exhibited excellent passivation for high open-circuit voltage. We have successfully achieved the large-area (156 × 156 mm2) n-PERT bifacial solar cells yielding top efficiency of 21.15%, together with a promising short-circuit current density of 40.40 mA/cm2. Theoretical calculation has further demonstrated that the optimal thickness of SiOx nano-layer will increase from 1.5 nm to 1.8 nm if the density of interface defect state decreases by one magnitude from 1 × 1010 cm−2/eV, and the cell efficiency can be improved up to 24.64% with open-circuit voltage over 0.720 V by optimizing the parameters of functional materials and interface layers. The present work has indicated that the commercialization of low-cost and high-efficiency n-PERT bifacial c-Si cells is possible due to the processes compatible with existing production lines.

The SiN/SiO2 stack is widely used to passivate the surface of n-type monocrystalline silicon solar cells. In this work, we have undertaken a study to compare the stack layer obtained with SiO2 grown by both rapid thermal and chemical ways to passivate n-type monocrystalline silicon surface. By varying the plateau time and the plateau temperature of the rapid thermal oxidation, we determined the parameters to grow 10 nm thick oxide. Two-step nitric acid oxidation was used to grow 2 nm thick silicon oxide. Silicon nitride films with three refractive indices were used to produce the SiN/SiO2 stack. Regarding this parameter, the minority carrier lifetime measured by means of QSSPC revealed that the refractive index of 1.9 ensured the best passivation quality of silicon wafer surface. We also found that stacks with nitric acid oxidation showed definitely the best passivation quality. In addition to produce the most efficient passivation, this technique has the lowest thermal budget.

Boron-diffused samples passivated by Al2O3/TiO2 stacks with different types of TiO2 were investigated. An emitter saturation current density of 11 × 10−15 A/cm2 was obtained for Al2O3/TiO2 passivated samples with symmetrical 100 Ω/sq. boron diffusion. The surface passivation of Al2O3/TiO2 stacks was strongly impacted by the temperature, gas, and sequence during two-step annealing. In addition, the saturation current density of the Al2O3/TiO2 stacks is influenced by the TiO2 layers with an O3 treatment. Enhanced passivation performance of the Al2O3/TiO2 stacks was achieved by a combination of appropriate TiO2 capping layer and post-annealing. The results of this study provide reliable criteria for the design of thermally-stable Al2O3/TiO2 stacks on high-efficiency silicon solar cells.

The silicon solar cells achieved relatively low prices in the last years and to introduce a new structure in the PV industry, the amount of silicon per watt has to be reduced, requiring a cost-effective manufacturing process. The use of n-type solar grade silicon has the advantages of presenting higher minority carrier lifetime than p-type one and the absence of the boron-oxygen defects. The aim of this paper is to present the development of 100 μm thick n+np+ silicon solar cells with a selective p+ rear emitter formed by boron deposited by spin-on and an Al/Ag grid deposited by screen-printing. The firing temperature of Ag/Al (rear face) e Ag (front face) was optimized and the temperature of 840 °C produced the devices with higher efficiency. The solar cells presented efficiencies of 16%, achieving a low silicon consumption of 1.6 g/W, 40% lower than thick p-type devices produced by the same process.

This paper outlines the development of fully screen-printed, uniformly diffused, bifacial, n-type silicon solar cells produced using a lean processing sequence and industry-standard equipment. An average batch efficiency of 21.4% was measured at standard test conditions for an optimised bifacial cell batch (i.e. illumination on the front surface only). The results of open circuit voltage (VOC) and fill factor (FF) loss analyses are presented for select batches. By targeting reductions in the largest recombination components, optimised batch VOC was increased by 15 mV compared to the baseline case. The two largest recombination components limiting VOC in optimised devices are front contact recombination and passivated rear surface recombination. The largest FF loss components for optimised devices are the emitter sheet resistance and front contact resistance.

N-type multicrystalline silicon (mc-Si) is a promising alternative to the dominant p-type mc-Si for solar cells because it combines the cost advantages of mc-Si while benefiting from higher tolerance to transition metal contamination. A detailed understanding of the relative roles of point defect and precipitated transition metals has enabled advanced processing and high minority carrier lifetimes in p-type mc-Si. This contribution extends that fundamental understanding to Fe contamination in n-type mc-Si, helping enable processing of this material into an economical and high-performance photovoltaic device. By directly correlating micro-photoluminescence-based minority carrier lifetime mapping and synchrotron-based micro-X-ray fluorescence mapping of Fe-rich precipitates, we develop a quantitative, physical understanding of the recombination activity of Fe-rich precipitates in n - type mc-Si.

In this contribution, we demonstrate a route for efficiencies exceeding 22% with n-type multicrystalline (mc) silicon solar cells based on the TOPCon cell concept featuring a boron-diffused front side emitter and a full-area passivating rear contact. By applying a “high-performance” (HP) crystallization process with an adapted seed structure in order to obtain an optimized grain boundary area fraction, we reduce recombination losses in the HP mc-Si material to a minimum. We discuss the electrical properties of the optimized n-type HP mc-Si, which features very low material-related efficiency losses of approximately 0.5% abs and, thus, enables an efficiency potential of 22.6% with regard to a cell limit of 23.1% of the TOPCon cell concept adapted for multicrystalline silicon. Results at the device level reveal a record efficiency of 21.9%, which is the highest efficiency reported for a multicrystalline silicon solar cell. Finally, we discuss the deviations between the predicted efficiency potential and the solar cell results.

It is shown that photocurrents along p+ and n+-type layers of a locally probed p+-n(p)-n+ silicon structure inhomogeneous in area can lead to a substantial drop of contrast of microwave photoconductivity in comparison to its intrinsic contrast. The study is performed using a model with two solar cells connected by a resistor, in which one of the solar cells is illuminated.

We present 6-inch n-type Cz-Si metal wrap through (MWT) solar cells with screen-printed and fired contacts achieving energy conversion efficiencies up to 20.4%. These so-called n-type high-performance MWT (n-HIP-MWT) structures feature different rear side configurations at the external p-type contacts with respect to the phosphorus-doped back surface field (BSF). It is shown that the alteration of the phosphorus dopant concentration at the silicon surface below the external rear p-type contacts allows for both decreasing reverse-bias-induced losses and adjusting the current flowing in reverse mode.

In this paper, we study a light-induced degradation (LID) mechanism observed in commercial n-type silicon heterojunction (SHJ) solar cells at elevated temperatures using dark- and illuminated annealing for a broad range of illumination intensities (1–40 kWm−2) at temperatures from 25 to 180 °C. Three key results are identified. Firstly, an increase in solar conversion efficiency (η) of up to 0.3% absolute is observed after 3 min of dark annealing at 160 °C, attributed to improved surface passivation and a reduction in series resistance. Secondly, a temperature-dependent light-induced degradation behaviour is observed at temperatures as low as 85 °C under 1-sun equivalent illumination, with increasing degradation extent and rate for increasing temperatures. At 160 °C, an average η loss of 0.5 ± 0.3% absolute is observed after only 5 min and exceeding 0.8% in some cells. Thirdly, a subsequent light intensity-dependent recovery occurs with continued illumination exposure. Under 1-sun illumination at 160 °C, a reduction in net η loss up to 0.05 ± 0.1% absolute is observed after 2 h. Increasing the illumination intensity to 40 kWm−2 accelerates the recovery and can result in a net η improvement of 0.2% absolute at 150 °C within 100 s. The results suggest that attempts to improve the efficiency of SHJ solar cells using illuminated annealing could be detrimental to cell performance if not carefully optimised. Further investigation is required to identify the exact nature of the underlying defect mechanism(s) and develop appropriate mitigation strategies on commercially suitable timescales.

Based on the surface passivation of n-type silicon in a silicon drift detector (SDD), we propose a new passivation structure of SiO2/Al2O3/SiO2 passivation stacks. Since the SiO2 formed by the nitric-acid-oxidation-of-silicon (NAOS) method has good compactness and simple process, the first layer film is formed by the NAOS method. The Al2O3 film is also introduced into the passivation stacks owing to exceptional advantages such as good interface characteristic and simple process. In addition, for requirements of thickness and deposition temperature, the third layer of the SiO2 film is deposited by plasma enhanced chemical vapor deposition (PECVD). The deposition of the SiO2 film by PECVD is a low-temperature process and has a high deposition rate, which causes little damage to the device and makes the SiO2 film very suitable for serving as the third passivation layer. The passivation approach of stacks can saturate dangling bonds at the interface between stacks and the silicon substrate, and provide positive charge to optimize the field passivation of the n-type substrate. The passivation method ultimately achieves a good combination of chemical and field passivations. Experimental results show that with the passivation structure of SiO2/Al2O3/SiO2, the final minority carrier lifetime reaches 5223 μs at injection of 5×1015 cm−3. When it is applied to the passivation of SDD, the leakage current is reduced to the order of nA.

In this study, the influence of ambient temperature on the performance of p and n types of silicon solar cells have been investigated. The PC1D modeling software is used to simulate and analyze the photovoltaic properties of both types of silicon solar cells with the total thickness is restricted to $1\mu m$ and the ambient temperature is varied from 20 to 50°C. The simulation result exhibits the n type silicon solar cell give a better performance in term of short circuit current density compared to n type silicon solar cell. Apart from that, the conversion efficiency of silicon solar cells decrease linearly to ambient temperature due to higher recombination current. The efficiency of 5.58% is achieved for both types of silicon solar cells with ambient tempearture of 20°C.

Atomic-layer-deposited titanium oxide (TiOx) is examined for the application as electron-selective full-area contact to n−type silicon solar cells. Although the surface passivation quality of TiOx-...

Here, we report for the first time on the controlled and accurate photoelectrochemical etching of macropores in n-type silicon in hydrofluoric acid-based electrolytes at anodic voltages below the electropolishing peak value down to quasi-zero Volt. Our results break a new ground on the controlled electrochemical dissolution of n-type silicon by further improving flexibility of this technology and pushing it towards commercial microelectronic applications. In the last few years the electrochemical micromachining (ECM) technology, which is based on the photoelectrochemical etching (PECE) of n-type silicon, is increasingly emerging as a promising silicon microstructuring technique alternative to standard both dry and wet etching tools1. A number of high aspect-ratio three-dimensional microstructures and microsystems have been reported over the past 10 years with applications ranging from automotive and biomedics to microelectronics and nanomedicine. The golden rule for the controlled PECE of macropores in low doped n-type silicon states to conduct the etching at anodic voltage values (Vetch ) above the electropolishing voltage value VPS (typically of a few Volts)2-5. Nonethless, even at Vetch >VPS there are a few constraints that limits the feasibility of macropores with arbitrary size and pitch. Specifically, it has been suggested that the maximum diameter of stable pores (about 10 μm for silicon of a few Ωcm) depends on the resistivity of the silicon substrate3,5. Moreover, the maximum pore pitch (about 20 μm for silicon of a few Ωcm) appears to be roughly limited to twice the depletion region at the silicon/electrolyte interface3. The starting material is a (100) oriented, n-type silicon wafer, with a resistivity of 3÷8 Ω∙cm and thickness of 750 μm, provided with a thermally grown 200-nm-thick silicon dioxide layer. A square lattice of holes with side of 4 μm and pitch of 20 μm was defined on the front surface of the silicon wafer by standard photolithography followed by buffered hydrofluoric acid (BHF) etching of the silicon dioxide and potassium hydroxide etching of silicon through a photoresist mask. Patterned wafers were electrochemically etched for 6000 s under back-side illumination (250 W halogen lamp) by using an aqueous solution of HF (concentration of 5% by vol). The current density/voltage (J/V) curve of the n-type silicon-electrolyte system under investigation has an electropolishing peak (VPS , JPS) at JPS =70.0 mA/cm2 (± 0.5 mA/cm2) and VPS =1.2 V. The same initial current density value Jetch0 =4.8 mA/cm2 was used for all the experiments. The Jetch value was then varied over time to ensure the etching of macropores with constant diameter over depth1,2,4. The anodic voltage values Vetch was varied among the different experiments from 0 to 2 V. Eventually, the electrochemically etched wafers were rinsed in ethanol and dried at 60 °C for 10 min. For each Jetch-Vetch parameter pair were performed 3 experiments, at least. Notice that, three of the Vetch values (i.e. 0, 0.4 and 0.8 V) are below the electropolishing peak value VPS and one is above (i.e. 2 V). Macropores etched at Vetch >VPS (i.e. 2 V) show a significant lateral branching and, in turn, a major roughness on the inner surface. This was somehow expected as both pitch (about 20 μm) and size (about 10 μm) are at close to the maximum features controlled by PECE according to the state-of-the-art literature3. On the contrary, the etching at Vetch

Al 2 O 3 nanolayers, as currently used in the solar industry, provide excellent passivation over the entire injection level range for p -type Si. A high concentration of negative fixed charges guarantees excellent field effect passivation. However, on n -type Si, those fixed charges create an inversion layer at the surface, which opens an additional near-surface recombination channel. This results in a reduced minority carrier lifetime at low injection levels, which is the operation condition of solar cells. In this work, a passivation layer stack is presented, showing excellent performance within the complete injection level range symmetrically for both p - and n -type Si. This layer stack consists of 20 nm Al 2 O 3 combined with a thin HfO 2 or SiO 2 interface. Electrical measurements show a reduction of the fixed charge density to virtually ‘zero’, when the interface layer is adjusted accordingly. This affects the field effect passivation and leads to a decrease of the near surface recombination in n -type Si. The introduction of five cycles of atomic layer deposited HfO 2 improves the effective carrier lifetime in passivated n -type Si from 6 to 15 ms at an injection level of 5×10 12 cm − 3 . The same passivation stack hardly influences the lifetime in p -type Si. The effective surface recombination velocity reaches values below 1 cm/s for both types of substrate doping. In case of the introduction of a 1 nm thick SiO 2 interface, which also results in ‘zero’ fixed charges, the surface recombination velocity reaches a value of up to 200 cm/s due to enhanced surface recombination. The comparison of both passivation stacks shows that the introduction of an ultrathin HfO 2 interface is the most promising approach to achieve a symmetrical passivation layer for p - and n -type Si.

Several industrial n-type Czochralski silicon ingots were analysed on wafer and cell levels with ECN׳s bifacial n-type solar cell process. In some of the ingots, the solar cell performance in the very top drop of about 1% absolute with respect to cell from the middle part of the ingot. These cells show typical ring shaped pattern. After receiving a post-process anneal treatment at 200 °C, the efficiency nearly completly recover. We demonstrated that the improvement is due to bulk lifetime enhancement. The recovery is stable in storage conditions, under illumination and high temperature treatments up to 600 °C. The same effect cannot be reproduced in p-type Cz silicon solar cells with similar ring shaped patterns. This indicates that the defects responsible for lifetime and efficiency degradation in wafers affected by ring patterns differ in n-type and p-type.

In this work, deep levels introduced by RTA and by subsequent anneals in n-type silicon were studied by deep level transient spectroscopy and by photoluminescence. After annealing at 650 {degree sign}C, centers related to rod-like defects appeared. Furthermore, signals related to thermal donors were found in a wide temperature range. New thermal donors were found even after annealing at temperatures above 900 {degree sign}C. The appearance of rod-like defects indicates that during cooling after RTA soak interstitials supersaturate. The appearance of rod-like defects is accompanied by a decrease of the thermal donor concentration

The photoanodes with heterojunction behavior could enable the development of solar energy conversion, but their performance largely suffers from the poor charge separation and transport process through the multiple interfacial energy levels involved. The question is how to efficiently manipulate these energy levels. Taking the n-Si Schottky photoanode as a prototype, the undesired donor-like interfacial defects and its adverse effects on charge transfer in n-Si/ITO photoanode are well recognized and diminished through the treatment on electronic energy level. The obtained n-Si/TiOx/ITO Schottky junction exhibits a highly efficient charge transport and a barrier height of 0.95 eV, which is close to the theoretical optimum for n-Si/ITO Schottky contact. Then, the holes extraction can be further facilitated through the variation of surface energy level, with the NiOOH coated ITO layer. This is confirmed by a 115% increase in surface photovoltage of the photoanodes. Eventually, an unprecedentedly low onset po...

Secco etchant was conventionally used for delineation of flow pattern defects (FPDs) in lightly-doped Czochralski (Cz) silicon wafers. However, the FPDs in heavily doped n-type silicon wafers cannot be well delineated by Secco etchant. Herein, an etchant based on CrO3-HF-H2O system, with an optimized volume ratio of V(CrO3): V(HF)=1:1, where the concentration of CrO3 is 0.25 M, has been developed for delineation of FPDs with well-defined morphologies for the heavily As- or P-doped n-type silicon wafers.

This paper describes results of metal wrap through (MWT) cells produced from n-type Czochralski silicon wafers, and modules produced from those cells. The use of n-type silicon as base material allows for high efficiencies: for front emitter contacted industrial cells, efficiencies upto nearly 20% have been reported. MWT cells allow even higher cell efficiency, and additionally full back-contacting of the MWT cells in a module results in reduced cell to module (CTM) losses. MWT cells were produced by industrial process technologies. The efficiency of the MWT cells reproducibly exceeds the front contact cells based on the same technology by about 0.2-0.3%, and routes for further improvement are analysed. 60-cell modules were produced from both types of cells. The MWT module, based on integrated backfoil, produced 3% higher power output than the comparable tabbed front emitter contact module. In particular differences in CTM loss of current and fill factor will be presented. CTM current differences arise from the higher packing density, and lower reflectance of the backfoil, in MWT modules. CTM FF differences are related to resistive losses in copper circuitry on the backfoil versus tabs. The CTM FF loss of the MWT module was 2.2%abs lower than for the tabbed front emitter contact module. Also here the losses are analysed and routes for improvement discussed.

We have applied Rosenbrock's optimization algorithm to obtain the optimized efficiency of a solar cell and its structural parameters. To obtain these parameters. we have developed a computer pro-ram for simultaneous optimization and simulation of the solar cell. We have used experimental data on the electrical and optical properties of a-Si(1-x)C(x) layers, put them into the written code and obtained the optimized parameters of this solar cell. The maximum efficiency is 6.32% which is close to one experimental result. (C) 2004 Elsevier B.V. All rights reserved.

Carrier transport and photodetection in heterojunction photodiodes comprising n-type Si substrates and p-type B-doped ultrananocrystalline diamond/hydrogenated amorphous carbon composite (UNCD/a-C:H) films were investigated. Their transport model was discussed mainly on the basis of electrical measurements. It was revealed that an a-C:H matrix in UNCD/a-C:H would predominantly be responsible for carrier transportation in the photodiodes. The photodiodes exhibited high external quantum efficiencies of 72 and 23% under 254 and 365 nm UV illuminations, respectively. These superior responses might be attributable to the photocarrier generation in UNCD grains accompanied by an efficient carrier transport to the a-C:H matrix.

Aluminium-doped p-type (Al-p+) silicon emitters fabricated by means of a simple screen-printing process are effectively passivated by plasma-enhanced chemical-vapour deposited amorphous silicon (a-Si). We measure an emitter saturation current density of only 246 fA/cm2, which is the lowest value achieved so far for a simple screen-printed Al-p+ emitter on silicon. In order to demonstrate the applicability of this easy-to-fabricate p+ emitter to high-efficiency silicon solar cells, we implement our passivated p+ emitter into an n+np+ solar cell structure. An independently confirmed conversion efficiency of 19.7% is achieved using n-type phosphorus-doped Czochralski-grown silicon as bulk material, clearly demonstrating the high-efficiency potential of the newly developed a-Si passivated Al-p+ emitter. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Effects of screen-printed aluminum-alloyed front emitter (AAFE) on characteristics of screen-printed N-type silicon solar cells (SPNSSC) were presented. The sheet resistances of AAFE in SPNSSCs can be modified by the firing temperature, the firing time, the waiting time, and the etching time of the KOH solution. The results show that the sheet resistance decreases with increasing the firing time, and the firing temperature. On the other hand, the sheet resistance increases with increasing the waiting time as well as the etching time of the KOH solution. Moreover, the larger thickness of AAFE can be achieved by the increase of the firing temperature and time. The optimum conversion efficiency can be obtained by suitably turned process parameters.

Bipolar components that consist of p+n junctions have been irradiated by MeV protons at fluences ranging from 1011 to 1013 particles cm−2. Capacitance‐voltage measurements have been used to investigate changes in the carrier concentration profiles. Shallow donors that can induce harmful effects in electronic devices have been studied as a function of fluence, flux, and annealing parameters.

Today's photovoltaic (PV) industry is growing up at a rapid rate, but it could be faster by reducing costs for both the final products and the capital investment required for scale-up. In this work, we have studied the possibility to use conventional silicon solar cell for low concentrated applications (X10–X100). The first result is that p type bulk silicon, as it was used in conventional solar cells technology, gives best results than n type only for the Jsc parameter. For concentration factors in the range X = 10 to 20, higher efficiencies (η = 16%) are obtained with the two type of solar cells.

Visible luminescence observed from the nanoporous layer of the two (100)-orinted low doped and highly doped PEC-etched n-type Si is explained as being due to the existence of single crystal silicon quantum wires within their structure. The nanometer-size tangled Si structure is contained and attached to a regular geometric Si macroarray. TEM studies also reveal subtle variations in morphology between the two layers studied, which could explain the blueshift in the spectrum of the low-doped specimen — thinner and more rigid irregular wires — as compared to the highly doped specimen.

The structural and electrical properties of n-type silicon strained layers, sandwiched between Si1−xGex layers, with x=0.15, 0.20 and 0.30 have been investigated using a combination of analytical techniques. Here, the focus is on the application of deep level transient spectroscopy (DLTS) on p–n junction structures, to assess non-radiative generation-recombination centres. It will be demonstrated that successful analysis can only be applied if the edges of the devices are chemically passivated. Finally, it is shown that for low-leakage diodes, the quantum-well properties can, in principle, be extracted from the combined DLTS and capacitance–voltage/capacitance–temperature characteristics.