N-type Silicon Wafers Research Articles

Magnetic bipolar transistor based on ZnO/NiO/Si heterostructure using pulsed laser deposition

Oxide semiconductors are promising candidates for next generation electronics. In this work, magnetic bipolar transistor was fabricated by growing thin films of p-NiO and n-ZnO on n-type silicon wafer by pulsed laser deposition technique with an in-situ annealing at 670° C in the presence of oxygen. The structural characterization of these films was done by X-ray diffraction and Raman spectroscopy and magnetic properties were studied by vibrating sample magnetometer (VSM). I-V characteristic of fabricated transistor was tested in common emitter configuration with DC biasing. Junction parameters such as ideality factor, series resistance, and transistor parameters like q-point were determined by using conventional transistor output characteristics. The diode and transistor showed an increase in current with the externally applied magnetic field due to the presence of Nickel or Oxygen vacancies in NiO attributing to spin polarized bipolar transport. Therefore the current amplification in these devices can be controlled by spin; making it attractive for spintronic applications.

Hydrogen-induced degradation: Explaining the mechanism behind light- and elevated temperature-induced degradation in n- and p-type silicon

Light- and elevated temperature-induced degradation (LeTID) has been extensively studied on p-type silicon materials with increasing evidence suggesting the involvement of hydrogen. Recent findings of the identical phenomenon in n-type silicon wafers have further opened up new areas of understanding into the inherent behavior and root cause of the defect. In this work, we compare LeTID observed in both p- and n-type silicon wafers under both dark and illuminated annealing conditions, highlighting previously unobserved similarities in defect formation and recovery kinetics. We report thermal activation energies of the LeTID-related degradation and recovery in n-type silicon to be 0.76 ± 0.02 eV and 0.97 ± 0.01 eV without illumination, respectively, and 0.70 ± 0.05 eV and 0.83 ± 0.15 eV under illumination (0.02 kWm−2), respectively. Furthermore, we present additional experimentation demonstrating the thermal and illumination dependency of surface-related degradation (SRD) in n-type silicon. We report an extracted activation energy of this SRD of 0.38 ± 0.10 eV. Through modelling of the hydrogen charge state fractions, we speculate that the behavior of LeTID both in the dark and under illumination may be explained by the migration of and interactions between charged hydrogen species and dopant atoms within the diffused layers and the silicon bulk.

Photo-Responses of Silicon Photodiodes with Different ARC Thicknesses for Scintillators

We designed and fabricated silicon positive-intrinsic-negative (PIN) photodiodes coupled with a scintillator for radiation detection. The photodiodes were fabricated on an n-type double-sided polished silicon wafer with a diameter of 6-in., a high resistivity ( orientation. To increase the quantum efficiency (QE) of the photodiode, an anti-reflection coating (ARC) was provided on the side where light entered. It is difficult to realize an ARC with an uniform thickness in the sensor fabrication process. The effect of changes in the ARC thickness on the QE of the fabricated sensors was studied in detail. We measured the electrical characteristics and compared their quantum efficiencies as a function of the incident light wavelength for the photodiodes with different ARC thicknesses. In this paper, we present the design of the photodiodes and their measured electrical characteristics and photo-responses for different ARC thicknesses. From measurements of the wavelength-dependent QE, we determined the refractive index of the ARC layer to be 2.25 ± 0.15. The ARC layer improved the QE up to 56% and 63% at the wavelengths of 550 and 475 nm, which correspond to the wavelengths of the scintillation light from CsI(Tl) and CdWO4, respectively.

24.58% total area efficiency of screen-printed, large area industrial silicon solar cells with the tunnel oxide passivated contacts (i-TOPCon) design

We demonstrate an “industrial tunnel oxide passivated contacts” (i-TOPCon) silicon solar cell on large area n-type silicon wafers (156.75 mm × 156.75 mm). This cell has a boron diffused front emitter, a tunnel-SiOx/n+-poly-Si/SiNx:H structure at the rear side, and screen-printed electrodes on both sides. The passivation of the tunnel-SiOx/n+-poly-Si/SiNx:H structure on silicon wafers is investigated. The saturation currents Jo of this structure on polished and textured silicon surfaces are 1.3 and 3.7 fA/cm2, respectively. After printing the Ag contacts, the Jo of this structure increases to 50.7 fA/cm2 on textured silicon surfaces, which is still manageably low for metal contacts. This structure was applied to i-TOPCon solar cells, resulting in a median efficiency of 23.91%, measured in-house, and a champion efficiency of 24.58%, independently confirmed by the ISFH CalTeC in Germany. The champion efficiency was measured with total area illumination, including screen-printed fingers and busbars.

Effect of post-deposition annealing on atomic layer deposited SiO2 film for silicon surface passivation

We have investigated the passivation performance of atomic layer deposited silicon dioxide (ALD-SiO2) films on crystalline silicon surface with various post-annealing temperatures. A maximum effective lifetime of 2157 μs can be achieved at the optimized annealing temperature of 650 °C on 3 Ω cm n-type silicon wafers. The improved passivation quality can be attributed to the low interface defect density and extremely high positive fixed charge density. Especially, the high positive fixed charge density of over 4 × 1012 cm-2 can be observed after annealing at high temperature. Therefore, it is inferred that the passivation mechanism for ALD-SiO2 films is based on not only chemical passivation but also field-effect passivation, which is more similar with the ALD-Al2O3 films rather than the thermally grown SiO2 films. X-ray photoelectron spectroscopy, secondary ion mass spectroscopy and thermal effusion measurement revealed the variation of elements content and distribution of silicon, oxygen, hydrogen and carbon during the post-deposition thermal treatment process, indicating that the rearrangement and release of these elements create more oxygen vacancies and result in the improvement of interface quality and positive fixed charge density of ALD-SiO2 films.

Contact charge transfer between inorganic dielectric solids of different surface roughness

We measured contact charge transfer between chemically identical, dielectric solids with different surface roughness. Glass of four different roughness levels had its own charge transfer series with the rougher glass negative with respect to the smoother in all combinations. Unpolished N-type silicon wafers became negative to polished N-type wafers; P-type wafers showed the opposite behavior. Rougher glass was more negative than smoother glass after contact with chemically non-identical samples. The results are consistent with modeling studies that show that the concentration of excited electrons is lower in solids in which there is greater access to surface de-excitation.

Electrical and Photovoltaic Responses of an Au/Coumarin 337/n-Si/Sb-Au Hybrid Organic–Inorganic Solar Cell

Thin films of coumarin 337 (C-337) dye were fabricated on n-type silicon (111) wafer using a high-vacuum thermal evaporation technique. Investigation of their structure using x-ray diffraction analysis and scanning electron microscopy revealed that the pristine C-337 films had sphere-shaped nanostructure. The absorbance, transmittance, and reflectance of the C-337 films were measured spectrophotometrically. Tauc’s method revealed an indirect allowed-type optical transition for these films with an optical band gap of 1.59 eV assisted by phonons of 52 meV. Hybrid organic–inorganic heterojunction solar cells based on C-337 were deposited on n-type single-crystal silicon wafer. Many aspects of the electrical parameters of the Au/C-337/n-Si/Sb-Au heterojunction solar cells were studied under dark condition based on their capacitance–voltage, conductance–voltage, and current–voltage characteristics at different frequencies (100 kHz to 1 MHz). The Nyquist diagram of the solar cell was recorded at various frequencies. Furthermore, the illuminated current–voltage and phototransient characteristics of the cell were also measured and used to evaluate the photovoltaic performance of the device. Under illumination intensity of 90 mW/cm2, the solar cell showed good photovoltaic behavior with short-circuit current, open-circuit voltage, fill factor, and power conversion efficiency of 5.42 mA, 0.55 V, 0.59, and 4.39%, respectively. The photovoltaic and phototransient properties of the device indicate that it could be applied as both a solar cell and a linear dynamic range optoelectronic switching sensor.

SnO2/Mg combination electron selective transport layer for Si heterojunction solar cells

In this paper, SnO2 prepared by sol-gel method was spin-coated on textured n-type crystalline silicon (c-Si) wafers to replace phosphorus doped n-type hydrogenated amorphous silicon (a-Si:H) in novel Si heterojunction (SHJ) solar cells. Good coverage of the sol-gel SnO2 layer on pyramidal textured silicon substrate was achieved. It was demonstrated that a low-work-function metal electrode is necessary for the dopant-free electron transport layer. The SnO2/Mg combination layer was determined to have a low-work-function feature and exhibit a synergistic effect in promoting the selective transport of carriers. A combination passivation layer containing intrinsic amorphous silicon (a-Si:H(i)) and SiOx which was formed from UV-O3 photo oxidation of the a-Si:H(i) surface for a short time was used to passivate the interface between the SnO2 and the c-Si. The new type a-Si:H/SiOx/SnO2/Mg contact is effective to achieve not only a low contact resistivity but also good passivation properties. Finally, a power conversion efficiency (PCE) of 18.6% and an open circuit voltage of 695 mV was achieved on a novel SHJ solar cell with an a-Si:H(i)/SiOx combination passivation layer and a SnO2/Mg combination electron selective transport layer.

Electrochemical Behavior of Ga3+, NO3 - and NH4 + Ions and Electrodeposition of GaN in Aqueous Solutions

Gallium nitride (GaN) is one of the most interesting III-V semiconductor materials because its direct wide band gap (3.39 eV) at room temperature, which has a wide use in optical devices operating at blue and ultraviolet wavelengths, and its promising potential for semiconductor optical and electronic devices, which are suitable for high temperature, high power, and high-frequency applications. In the last few decades, many studies have been reported on the growth of GaN thin films using various techniques such as metalorganic chemical vapor deposition (MOCVD), reactive molecular beam epitaxy (MBE) and hydride vapor phase epitaxy (HVPE), etc. However, these require very expensive equipment and well-defined environments, such as ultra-high vacuum and high temperature. Therefore, we can think of an economical electrodeposition as an effective way to replace existing methods. Electrodeposition is very economical and environment-friendly method compared to previous techniques because it is very simple to use and can synthesize materials at room temperature. Therefore, a simple and inexpensive electrodeposition technique was adopted for the synthesis of GaN film in this study. For the synthesis of GaN, gallium nitrate (Ga(NO3)3) and gallium chloride (GaCl3) were used as gallium sources, and ammonium nitrate (NH4NO3) and ammonium chloride (NH4Cl) were selected as nitrogen sources. Prior to deposition, cyclic voltammetry analysis was performed to check the electrochemical behavior of each ion in the solution. An n-type silicon wafer was used as a working electrode and a platinum coil was used as a counter electrode. The reference electrode was an Ag|AgCl|KCl. The pH of all solutions was adjusted to 1.5. To unify the ion species present in the bath, hydrochloric acid (HCl) was used to adjust the pH of the solutions containing GaCl3 or NH4Cl, and nitric acid (HNO3) was used for the solutions containing Ga(NO3)3 or NH4NO3 severally. The voltammogram was obtained from the solution containing one reagent each, and then compared with the graphs obtained from the mixed solution. The results revealed that nitrate ion (NO3 -) can be changed to other state (NO3 - → NO2 - → NH4 +) and a reduction peak of gallium was also confirmed in the solution. Therefore, it was considered that GaN can be synthesized on the Si substrate if the reduction reaction of gallium ions occurs between the steps of changing nitrate ions. The electrodeposition to synthesis GaN was carried out at current densities of 8 mA/cm2 for 6 h in mixed solutions containing Ga(NO3)3, and NH4NO3. The deposited GaN film showed a plate-like structure, and gallium, nitrogen and oxygen were uniformly present in this film. The presence of GaN film was also supported by XRD analysis. Photoluminescence showed that our sample exhibit blue luminescence and also confirmed the peaks are in good agreement with the band gap energy of GaN. Photoluminescence showed that the deposits exhibits a blue luminescence and also a peak is in good agreement with the band gap energy of GaN.

Optimization of IBC c-Si (n) Solar Cell Using 2D Physical Modeling

This research paper demonstrates the use of doping concentration effect of front surface field (FSF), back surface field (BSF), and emitter for high-efficiency of n-type monocrystalline silicon (c-Si) interdigitated back-contact (IBC) solar cells using Silvaco TCAD package. The integrated-back contact solar cell is considering as a promising structure due to its high conversion efficiency, thinner substrate, and low-temperature processing of the substrate configuration. From previous research works, the considered IBC cell of 150-μm thick n-type CZ silicon wafers with a half-pitch size of 500 μm is studied and improved for either product quality and lower operating costs. The optimum conversion efficiency of about 24.79% has been achieved with open-circuit voltage up to 726 mV under the AM1.5 spectrum. Furthermore, the solar incident angle plays a critical factor affecting the considered device characteristics and performance of the fixed PV modules.

Design, Optimization and Characterisation of IBC c-Si (n) Solar Cell

The integrated-back contact (IBC) solar cell has attracted wide attention due to its high conversion efficiency, low processing temperature, and thinner substrate from the emerging light trapping of silicon on the pyramidal textured surface. In this paper, a novel IBC solar cell design optimization based on the n-type crystalline silicon wafer was simulated in 2D using Silvaco TCAD tools and the obtained results were compared to the recently published works which allow us to identify the optimum IBC solar cell configuration. In addition, the 2D simulation results are compared to the obtained results by IMEC using SolayTec’ ALD (atomic layer deposition) technique. The numerical simulation leads to attaining 24.79% conversion efficiency and 726 mV open-circuit voltage for the considered n-type mono-crystalline silicon solar cell under the AM1.5 spectrum.

Probe assisted localized doping of aluminum into silicon substrates.

Precise control of dopant placement is crucial for the reproducible, and reliable, nanoscale semiconductor device fabrication. In this paper, we demonstrate an atomic force microscopy (AFM) probe assisted localized doping of aluminum into an n-type silicon (100) wafer to generate nanoscale counter-doped junctions within two nanometers of the silicon-air interface. The local doping results in changes in electrostatic potential, which are reported as contact potential difference, with nanoscale spatial resolution. In contrast to the literature where nano-mechanical defects in, or contaminants on, silicon substrates can result in measurable changes in the chemical potential of the near-surface, additional thermal treatment was needed to electrically activate the aluminum dopants in our current work. Unfortunately, the thermal activation step also caused the dopants to diffuse and geometric distortions in the doped area, i.e., broadening and blurring of the electrically distinct areas. The results from optimization efforts show that the "active" dopant concentration depended primarily on the thermal anneal temperature; additional AFM-tip dwell time during the aluminum implantation step had no meaningful impact on the electrical activity of the doped sites.

The effect of current density on the structures and photoluminescence of n-type porous silicon

Porous silicon (PS) layers were formed on n-type silicon (Si) wafers using Photo- electrochemical Etching technique (PEC) was used to produce porous silicon for n-type with orientation of (111). The effects of current density were investigated at: (10, 20, 30, 40, and50) mA/cm2 with etching time: 10min. X-ray diffraction studies showed distinct variations between the fresh silicon surface and the synthesized porous silicon. The maximum crystal size of Porous Silicon is (33.9nm) and minimum is (2.6nm) The Atomic force microscopy (AFM) analysis and Field Emission Scanning Electron Microscope (FESEM) were used to study the morphology of porous silicon layer. AFM results showed that root mean square (RMS) of roughness and the grain size of porous silicon decreased as etching current density increased and FESEM showed that a homogeneous pattern and confirms the formation of uniform porous silicon. The chemical bonding and structure were investigated by using Fourier transformation infrared spectroscopy (FTIR). The band gap of the samples obtained from photoluminescence (PL). These results showed that the band gap of porous silicon increase with increasing porosity.

Effect of Oxygen Precipitation in Silicon Wafer on Electrical Characteristics of Fully Ion-Implanted n-Type PERT Solar Cells

Fully ion-implanted n-type PERT solar cells with boron-implanted emitter and phosphorus-implanted back surface field were fabricated on the n-type silicon wafers obtained from the top part of the magnetic field-applied Czochralski ingot. It was observed that the electrical parameters are widely dispersed; among 11 solar cells, the best performing achieved 20.4% front side conversion efficiency, whereas the worst achieved 19.0%. Although the silicon wafers had low oxygen concentrations of 3–4 × 1017 atoms/cm3, the density of oxygen precipitates in the silicon wafers was on the order of 109 /cm3 as a consequence of the fully ion-implanted n-type PERT silicon solar cell processes. In addition, it was observed that the front side conversion efficiencies of the solar cells depended on the density of oxygen precipitates. Furthermore, the behavior of the oxygen precipitation during the fabrication processes of the solar cell is discussed.

Morphological and Electrical Properties of gold nanoparticles /macroPorous Silicon for CO2 Gas

In this work, the fine structure macro-porous silicon (macroPS) substrate was prepared by photo-electro-chemical etching of n-type silicon wafer. Ultraviolet illumination condition of wavelength 360nm wavelength and intensity of about 100mW/cm2 with etching current density of about 50 mA/cm2 and etching time 5 min was employed. The Hybrid device gold nanoparticles /macroPorous Silicon (AuNPs/macroPS) was fabricated by deposition AuNPs into mPS substrate Via immersion plating process of macroPS in the solution of HAuCl4 with the (10-3M) concentration and 2min immersion time. The characteristics of PS before and after immersion process were investigated by scanning electron microscopy (SEM), EDS, X-Ray diffraction (XRD), photoluminescence (PL) and Infrared spectroscopy (FTIR). The J-V characteristics of sandwich structure showed that the maximum sensitivity of the AuNPs/macro PS was about (90.5%)for compared with macro-PS substrate. The current-voltage characteristics were performed in primary vacuum with a base pressure of about 0.2mbar and CO2 with 1mbare concentrations. Significant enhancement was observed in sensitivity of the AuNPs/macroPS hybrid device and temporal response after deposition the AuNPs.

Ring defects in n-type Czochralski-grown silicon: A high spatial resolution study using Fourier-transform infrared spectroscopy, micro-photoluminescence, and micro-Raman

We investigated ring defects induced by a two-step anneal in n-type Czochralski-grown silicon wafers using a combination of high spatial resolution Fourier Transform Infrared Spectroscopy (FTIR), micro-photoluminescence (PL) mapping, and micro-Raman mapping. Through FTIR measurements, we show the inhomogeneous loss in interstitial oxygen with a positive correlation with the inverse lifetime. Using high-resolution micro-PL mapping, we are able to distinguish individual recombination-active oxygen precipitates within the rings with a decreasing density from the center to the edge of the sample. The radial inhomogeneity of the oxygen precipitates is likely to be related to variations in the distribution of grown-in defects. We also demonstrate that micro-Raman mapping reveals the oxygen precipitates without the smearing effects of carrier diffusion that are present in micro-PL mapping.

Fabrication of copper oxide based heterojunction thin film solar cells using sputtering

In this study, p-type CuO and Cu2O-based heterojunction solar cells were deposited via RF magnetron sputtering, and their properties were studied as a function of the working pressure present during their creation. Firstly, single Cu2O and CuO films were grown on glass substrates at various working pressures using RF magnetron sputtering, and their characteristics were investigated in terms of the optimal fabrication conditions applicable for solar cells. Then copper oxide was deposited on an n-type silicon wafer and post-annealed in a vacuum. The electrical, optical and structural properties of the fabricated heterojunction solar cells were then investigated and the power conversion efficiencies (PCE) of the fabricated p-type copper oxide/n-type Si heterojunction cells were measured using solar simulator. The results indicated that the PCE of the solar cells with CuO film (0.43%) was higher than that of the cells with Cu2O film (0.12%).

Silicon doping of GaP layers grown by time-modulated PECVD

We study the doping in GaP layers grown on n-type silicon wafer by time-modulated plasma-enhanced chemical vapour deposition with additional flow of silane. Classical and electrochemical (ECV) capacitance-voltage methods were performed on GaP/Si heterostructures and they demonstrate high electron concentration in the GaP layer and similar profiles. In addition, glow-discharge optical emission spectroscopy revealed high silicon content in GaP, which should be responsible for the detected high n-type doping.

Some of Electrical and Detection properties of nano silver oxide

Micro and Nano Ag2O3 thin films have been deposited using the Reactive Pulse Laser Deposition (RPLD) method. N-type silicon wafer was used as substrates. The prepared films were annealed at (400 -600) °C to produce the oxide films. Spectral Responsivity had been sensed more optically for green (560nm) and near IR (840nm). Response time reveals an enhancement with annealing temperatures.

Investigation optical properties and functional surface characteristics of nanoparticles based on porous silicon for applications in biomedicine

In this paper optical characteristics of porous silicon layers and nanoparticles are investigated. Samples were obtained by electrochemical anodic etching of n-type conductivity monocrystalline silicon wafers. It is shown that the surface morphology porous silicon samples are depending on etching technological parameters.