Search

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.

Metal-assisted etching has attracted increasing attention as a method to produce porous silicon (Si). We previously found that gold (Au)-particle-assisted etching and platinum (Pt)-particle-assisted etching cause general corrosion of the Si substrate, but not in the case of silver (Ag)-particle-assisted etching [A. Matsumoto, et al., RSC Adv., 10, 253 (2020)]. In this work, we discussed the mechanism of the general corrosion with electrochemical approaches. We demonstrated that potentials of the Au- and Pt-deposited Si during the metal-particle-assisted etching are higher than that of the bare Si in the etchant, but not in the case of the Ag-deposited Si. We also performed electrochemical etching of the bare Si by applying the potential during the Pt-particle-assisted etching, resulting in the formation of a mesoporous layer which was dissolved in the etchant. We concluded that the general corrosion occurs during the metal-particle-assisted etching due to the dissolution of the mesoporous layer formed by anodic polarization of the Si substrate.

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.

We developed a method of inverse problem solving in semiconductor photoacoustics based on neural networks application. Simple structured neural networks, trained on a large set of data obtained by the well–known theoretical models in the 20 Hz–20 kHz modulation frequency range, are applied to determine thermal diffusivity, coefficient of linear expansion and thickness of n–type silicon samples, using undistorted experimental photoacoustic signals. The efficiency of the neural networks was tested depending on the type of input data, showing the best performances in the case when signal amplitudes and phases are simultaneously presented to the network. Real–time parameter prediction is achieved together with high accuracy and reliability allowing one to perform the full characterization of a sample in the frequency domain.

During low-temperature annealing, the segregation of the alloying element leads to a strong enrichment of the surface layer, causing a rearrangement of the surface electron structure. This change in the electron structure is manifested in the characteristic energy loss spectra. Annealing of single crystals at 400–500 K leads to an increase in the density of surface electron states. As shown by the calculations of the surface potential using experimental data on the temperature dependence of the surface concentration, dopant segregation causes a linear increase in the surface potential.

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.

A simple fabrication process of an n-type silicon nanowire (SiNW) biosensor for sub-10 femtomolar (fM) concentration immunoglobulin detection was presented in this work. The SiNWs with different widths of 80-190 nm were fabricated using electron beam lithography and reaction ion etching techniques. The electrical characteristics of SiNWs with various widths were measured. And it can be observed that thin SiNW has high resistance, which is in agreement with electrical resistance theory. Furthermore, the surface of the fabricated SiNW was functionalized by 3-aminopropyltriethoxysilane for making the biosensor device to detect the binding of immunoglobulin G (IgG) molecules. The responsivity of the biosensor was investigated by observing electrical performance in response due to IgG with various concentration from 6 fM to 600 nanomolar (nM). The resistance changing ratio based on the current voltage (I-V) characteristics was analyzed and it increased with increasing of the IgG concentration. As a result, it demonstrated that the n-type SiNW biosensor has the ability to detect the IgG molecules with low concentration of 6 fM.

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.

Al2O3/TiO2 stacks formed by atomic layer deposition are known to provide a high level of passivation for boron-doped silicon. In previous works, the TiO2 layer was deposited on a pre-annealed Al2O3 layer, however this stack showed passivation degradation after post-deposition annealing. This work presents an alternative to using the as-deposited Al2O3 for the Al2O3/TiO2 stack, which shows no degradation of passivation after post-deposition annealing up to 400 °C. This approach simplifies the processing, allowing continuous layer deposition, and eliminates the undesirable vacuum breaking. This simplified processing leads to better thermal stability of the Al2O3/TiO2 stacks and a low emitter saturation current density. In order to understand the underlying mechanism of surface passivation, an investigation on the effect of thermal SiO2 on the passivation of the Al2O3/TiO2 stack was performed, which indicates that the TiO2 capping layer enhances the field-effect passivation for both the Si/Al2O3 and SiO2/Al2O3 structures.

In this letter, we investigate contacts of a low work function rare-earth metal, La, and its silicides on n-Si. LaSi x / ${n}^{-}$ -Si contacts show low Schottky barrier height ( $\varphi _{b}$ ) of around 0.25–0.4 eV and promisingly low contact resistivity ( $\rho _{c}$ ) on moderately doped ${n}^{+}$ -Si. However, on highly doped ${n}^{++}$ -Si, we find $\rho _{c}$ of LaSi x near one order higher than the TiSi x control. This experiment indicates that low $\varphi _{b}$ does not guarantee low $\rho _{c}$ on highly doped substrates. We further discuss reasons behind this phenomenon.

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.

The outdoor performance of n-type bifacial Si photovoltaic (PV) modules and string systems was evaluated for two different albedo (ground reflection) conditions, i.e., 21% and 79%. Both monofacial and bifacial silicon PV modules were prepared using n-type bifacial Si passivated emitter rear totally diffused cells with multi-wire busbar incorporated with a white and transparent back-sheet, respectively. In the first set of tests, the power production of the bifacial PV string system was compared with the monofacial PV string system installed on a grey concrete floor with an albedo of ~21% for approximately one year (June 2016&ndash, May 2017). In the second test, the gain of the bifacial PV string system installed on the white membrane floor with an albedo of ~79% was evaluated for approximately ten months (November 2016&ndash, August 2017). During the second test, the power production by an equivalent monofacial module installed on a horizontal solar tracker was also monitored. The gain was estimated by comparing the energy yield of the bifacial PV module with that of the monofacial module. For the 1.5 kW PV string systems with a 30&deg, tilt angle to the south and 21% ground albedo, the year-wide average bifacial gain was determined to be 10.5%. An increase of the ground albedo to 79% improved the bifacial gain to 33.3%. During the same period, the horizontal single-axis tracker yielded an energy gain of 15.8%.

This article has been withdrawn at the request of the author, on the basis of the need to add extra data related to the research work. The Publisher apologizes for any inconvenience this may cause. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal

An open photo-acoustic cell was used to measure the thermal diffusivity (TD) of silicon by photo-acoustic technique. The samples were heated for a period 3 h to perform sample annealing at 960, 1050, 1200 and 1300 °C in air. The TD of Si coated-silver (Ag/n-Si) was measured by fitting experimental data for the equation thermally thick in (RG) theory. For uncoated silver n-Si (single layer) samples, the TD can be obtained by fitting experimental data and by finding the intersection of the thermal thin and thermal thick (critical frequency f c ). It was found that when the annealing temperature was increased, the TD of the (n-type Si) samples was also increased. However, at a temperature of 1050 °C, the TD value of the Ag/n-Si samples was found to be 2.93 cm2 s−1. Beyond this point TD showed a degrading behavior due to a complete silver melting on silicon surface.

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.

In this paper electrical and thermal conductivity coefficients of heavily doped n-Silicon have been derived based on parabolic and modified density of states having band tails. The derivation uses Boltzmann transport equation with relaxation time arising from ionized impurity scattering mechanism as a dominant scattering mechanism compared to the phonon scattering mechanism where the calculations are made at room temperature. Note that semi-classical and quantum mechanics treatments are employed during discussion of scattering mechanisms and calculation of transport coefficients for parabolic and modified density of states having band tails considerations. There is significant variation of electrical and thermal conductivity as well as Weidman-Franz ratio as much as 30%, 101.86%, and 0.66% respectively.

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.

In this work, we demonstrate a form of minority carrier degradation on n-type Cz silicon that affects both the bulk and surface related lifetimes. We identify three key behaviors of the degradation mechanism; 1) a firing dependence for the extent of degradation, 2) the appearance of bulk degradation when wafers are fired in the presence of a diffused emitter and 3) a firing related apparent surface degradation when wafers are fired in the absence of an emitter. We further report a defect capture cross-section ratio of σn/σp = 0.028 ± 0.003 for the defect in n-type. Utilizing our understanding of light and elevated temperature induced degradation (LeTID) in p-type silicon, we demonstrate that the degradation behaviors in both n-type and p-type silicon are closely correlated. In light of numerous reports on the involvement of hydrogen, the potential role of a hydrogen-induced degradation mechanism is discussed in both p- and n-type silicon, particularly in relation to the diffusion of hydrogen and influence of hydrogen-dopant interactions.

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

The authors investigated the Nottingham effect of an n-type silicon semiconductor cathode in a quest for a practical solid-state cooler. The dependence of field emission cooling on the carrier concentration n in the range from 1015 to 1020 cm -3 was analyzed. The potential profile was obtained for a spherical tip with a radius R = 0.5 nm and was used to calculate the energy exchange Δe and the cooling power density Γ as a function of n and the temperature T. The energy exchange Δe was found to remain almost constant for 1019 cm -3 and decrease slowly as n further increased. In contrast, the current density j increased continuously with increasing n. As a result, the cooling power density Γ increased with increasing n, more rapidly at higher T. For n = 1016, 1018, and 1020 cm -3, a bias of V = 6.0 volts yields Γ = 0.49, 49, and 3202 watts/cm2 at 600 K and 2.0, 201, and 16560 at watts/cm2 at 900 K, respectively. This predicts a field emission cooling for micro-electronic devices even with a bias equivalent to several dry cells.

The evolution of irradiation-induced and hydrogen-related defects in n-type silicon in the temperature range 0 – 300 °C has been studied by deep level transient spectroscopy (DLTS) and minority carrier transient spectroscopy (MCTS). Implantation of a box-like profile of hydrogen was performed into the depletion region of a Schottky diode to undertake the DLTS and MCTS measurements. Proportionality between the formation of two hydrogen-related deep states and a decrease of the vacancy-oxygen center concentration was found together with the appearance of new hydrogen-related energy levels.

We present new experimental data on light-induced degradation due to the boron oxygen defect in compensatedn-type silicon. We are the first to show that both defect components known fromp-type silicon are formed in compensatedn-type silicon. A parameterization of the injection dependent recombination activity of the slower formed defect component is established. The formation kinetics of both defect components are studied and modeled under different conditions. It is found that the same rate factors as inp-type can describe the degradation, if the actual hole concentration under illumination is taken into account. The regeneration process known to permanently deactivate boron oxygen defects inp-type is successfully applied ton-type material and the illumination stability of the regenerated state is tested and proven.

A method to dope silicon ribbons is presented. The method consists on the spraying of the ribbons with a phosphoric acid solution followed by a recrystallization in an optical heating furnace. During the sample heating, as phosphoric acid is dehydrated the resulting phosphorous compounds are either evaporated or serve as source for phosphorous diffusion. Phosphorous is efficiently incorporated in silicon by solid-state diffusion during heating and directly mixed in the melted silicon. Experimental results show significant incorporation gradients along the samples׳ length. The origin of the incorporation gradient is analysed, by testing the effect of experimental parameters such as the argon flux and the recrystallization velocity and direction. It is shown that samples recrystallized in a downward direction have homogeneous doping profiles over most of the length.

Tungsten contacts deposited on n-type 4H-SiC substrates were annealed at temperatures from 700 to 1400 °C and the phase composition of the contact layers was analyzed by TOF-SIMS technique, X-ray diffraction method and scanning electron microscopy. W 5 Si 3 and WC were characterized as the main crystalline phases formed in the contact layer after annealing at 1400 °C and crystallite size was calculated as equal to 74 nm and 73 nm, respectively. Measurements of current–voltage characteristics showed that ohmic character of the contact was obtained after annealing at the highest applied temperature 1400 °C while I – V characteristics of 1200 °C annealed contact showed limited deviation from linearity. The specific contact resistivities equal to 2.42 × 10 −5 Ω cm 2 and 2.27 × 10 −5 Ω cm 2 were achieved for 1200 and 1400 °C annealed contacts, respectively. The mechanism of ohmic contact formation was proposed.