N-type Single Crystal Silicon Research Articles

Magnetic field modulation effect on photoelectric effect and its explanation in BiFe0.9Ni0.1O3/n-Si multiferroic heterojunction

This paper reports a heterojunction laminate consisting of Ni doped BiFeO3 thin film and n-type single crystal silicon semiconductor, in which the repeatable modulation effect on the photoelectric properties were achieved by applying external magnetic fields. More obviously, the response of photocurrent and photovoltage to the magnetic field is perfectly linear. This functional effect of sensing is mainly related to the guidance of the magnetic field to the photogenerated carrier transfer process in the heterojunction. The linear relationships between magnetic field and photocurrent, magnetic field and photovoltage have been proved through the derivation of the formulas. The heterojunction perfectly combines the functions of the sensor and the controller to reflect both the intensity of the magnetic field and the intensity of the light in the environment. This work provides an alternative and facile way to realize the multi-degree of freedom control for electrical signal and practicability of multifunctional devices.

Laser radiation, CDs and Pd-NPs: Three influential factors to enhance the hydrogen storage capacity of porous silicon

In This study, n-type single-crystal silicon was used to make porous silicon by electrochemical and photoelectrochemical methods to investigate the hydrogen storage capacity. Carbon dots are made via a hydrothermal method, and palladium nanoparticles are decorated on porous silicon by electroless and drip processes. The morphology of the structures has been investigated using field emission scanning electron microscope, atomic force microscope and X-ray diffraction. The samples' electrochemical characteristics and hydrogen storage capacity have been studied by cyclic voltammetry and chronopotentiometry methods. The results show that laser irradiation for 0.5 h on the back of silicon wafers during the etching prosses increases the storage capacity in porous silicon by 45%. Adding carbon dots and palladium nanoparticles to porous silicon made by the photoelectrochemical method increases hydrogen storage capacity by 29% and 64%, respectively. The hydrogen storage capacity in porous silicon made by the photoelectrochemical method simultaneously decorated with palladium nanoparticles and carbon dots was 1.02% by weight, which shows an increase of 82% compared to undecorated porous silicon.

Experimental study on the effect of impurity concentration on phonon and electronic transport properties of single-crystal silicon

Investigation of the impurity concentration dependence of phonon and electronic transports is essential for semiconductor devices requiring thermal management. However, the experimental study of phonon transport properties is limited compared to theoretical studies. Therefore, in this work, n-type single-crystal silicon with different impurity concentrations was prepared to measure group velocity and thermal conductivity using nanoindentation and spot periodic heating with infrared radiation thermometry, respectively. Phonon mean free path (MFP) was evaluated by analyzing the measured group velocity and thermal conductivity. Electron MFP was determined from thermal velocity and relaxation time based on mobility. The impurity concentration dependences of electron and phonon MFPs differed significantly. Electron MFP decreased from 53 to 4.6 nm when the impurity concentration was increased from 2.3 × 1014 to 7.0 × 1018 cm−3. In contrast, phonon MFP exhibited a constant value of approximately 36 nm for an impurity concentration ranging from 2.3 × 1014 to 1.6 × 1017 cm−3. However, upon a further increase in the impurity concentration to 7.0 × 1018 cm−3, the phonon MFP decreased to 30 nm. These findings are especially beneficial for the fabrication of high-performance nanostructured thermoelectric materials.

Controlling the movements of E. faecalis bacteria that carry a negative electric charge with an electric field

One of the main problems of bacteria sensors is that sufficient numbers of bacteria cannot approach and attach to the sensor surface. In this study, it has been suggested that an external electrical field can be applied to bacterial sensors to eliminate this problem. Moving Enterococcus faecalis (E. faecalis) bacteria, which carry a negative electric charge, in a desired direction with the effect of an electric field is an example of this. The Ag/PS/Si/In structures used as the sensor platform in the experiments were produced on n-type single crystal silicon by electrochemical etching method with 50% porosity and 1–5 μm pore size. Bacterial approach and removal experiments were carried out by immersing this PS-based structure in fluids containing E. faecalis bacteria and applying an electric field of 0–5 kV/cm in forward and reverse directions. Physical properties of the Ag/PS/Si/In structure were examined by immersing them in fluids containing live and dead E. faecalis bacteria and applying a fixed 7 kV/cm electric field value for 0–3 h. All experimental results were analyzed by impedance spectroscopy technique.

Structure and morphology of CrSi<sub>2</sub> layers formed by rapid thermal treatment

The formation of chromium disilicide layers on n-type single crystal silicon substrates (111) during rapid thermal annealing in heat balance mode by the methods of Rutherford backscattering, X-ray diffraction and transmission electron microscopy of cross sections was investigated. Chromium films of about 30 nm thickness were deposited by magnetron sputtering of a chromium target with argon ions onto silicon substrates at room temperature. The rapid thermal treatment was carried out in a temperature range of 200 to 550 °C in a heat balance mode by irradiating the substrates backside with a non-coherent light flux of quartz halogen lamps in a nitrogen ambient for 7 s. It was established that hexagonal phase of chromium disilicide formation with grain size of 150–300 nm occurs in a threshold manner when the temperature of rapid thermal treatment exceeds 400 °C. At the same time, there are strong changes in the films surface morphology and surface roughness, and a silicide-silicon interface occur. In this case the wavy film surface morphology practically repeats silicide-silicon interface morphology (the surface exactly replicates the interface). The mechanism of CrSi2/Si interface structure roughness formation based on consideration of Kirkendall effect and deformation-stimulated diffusion of vacancies is proposed and discussed. The research results of the structure and morphology of CrSi2 layers on silicon are well-correlated with the results of the Schottky barrier electrophysical measurements. The results obtained can be used in microelectronics for forming rectifying contacts and interconnects metallization for integrated circuits, as well as for thermoelectric and optoelectronic applications.

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.

Fabrication, electrical and photovoltaic characteristics of CuInGeSe4/n-Si diode

The CuInGeSe4 thin film was deposited onto n-type single crystal silicon wafers by the electron beam deposition technique. The Au/CuInGeSe4/n-Si/Al heterojunction device has been fabricated. The structure of the CuInGeSe4 thin film was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive X-ray analysis (EDX). The dark current–voltage characteristics of the Au/CuInGeSe4/n-Si/Al heterojunction diode have been studied at a temperature range of 303–383 K. Also, the photovoltaic properties were examined at different illumination intensities. The capacitance–voltage characteristics of the CuInGeSe4/n-Si heterojunction were studied at different temperatures in the dark.

The Development of a New Piezoresistive Pressure Sensor for Low Pressures

This paper presents the design methodology and fabrication process of a novel piezoresistive pressure sensor with a combined cross-beam membrane and peninsula (CBMP) diaphragm structure for micropressure measurements. The sensor is then analyzed through various experiments. The sensor is primarily designed based on the optimized sensitivity, and a finite-element method is used to predict the stresses that are induced in the piezoresistors and the deflection of the membrane under different pressures. Compared to other traditional diaphragm types, a significant increase in sensitivity can be achieved by the proposed sensor, and the membrane deflection and nonlinearity error considerably decrease. The sensor fabrication process is performed on an n-type single-crystal silicon wafer, and photolithography is used with five masks to fabricate the sensing elements. Additionally, piezoresistors are formed by boron implantation. The experimental results indicate that the fabricated sensor with the CBMP membrane yields a high sensitivity of 25.7 mV/kPa and a low nonlinearity of −0.28% full-scale span for a pressure range of 0–5 kPa at room temperature.

An improved structural design for accelerometers based on slotted eight-beam structure

PurposeThe purpose of this paper is proposed a new structure design for high performance accelerometer.Design/methodology/approachAn improved sensitivity structure considering sensitivity, natural frequency and cross-axis sensitivity is established and realized. The proposed structure was designed to improve the trade-off between the sensitivity and the natural frequency of piezoresistive accelerometer and eliminate the lateral sensitivity effect by the specific configuration, which is made possible by incorporating slots into the eight-beam structure. The mechanical model and its mathematical solution are established for calculating the sensitivity and natural frequency behavior of the designed structure. The developed sensor is fabricated on the n-type single-crystal silicon wafer and packaged for experiment. The accelerometer prototype was tested in the centrifugal machine and dynamic calibration system.FindingsThe experimental results show that the sensitivity of the designed sensor is 0.213 mV/(Vg) and the natural frequency of the sensor is 14.22 kHz. Compared with some piezoresistive accelerometers in literatures, the designed sensor possesses a suitable characteristic in sensitivity, natural frequency and transverse effect, which allows its usage in measuring high frequency vibration signals.Originality/valueThe accelerometer with slotted eight-beam structure shows a good performance in the static and dynamic experiments and can be used in measuring high frequency vibration signals.

Study of Physical and Optoelectronic Properties of CuInSe2/Si Heterojunction Solar Cells

CuInSe2 (CIS) solar cell has been prepared by use vacuum thermal evaporation technique, with different thickness on (n-type) single crystal silicon substrate with orientation (111), the sample is annealed in the thermal range (400-600) K. The (C-V) measurements indicate that the heterojunction of abrupt type, the capacitance decreases with increasing thickness and annealing temperature, while there is increasing in charge carriers concentration. The (I-V) characterization under illumination found to improve in efficiency of a solar cell with thickness and annealing temperature, the solar cell which have an optimal condition (t=750±20) NM, Ta=600K have higher efficiency among other cells (η =5. 6). A short circuit current density (Jsc) of (30mA/ cm2), open circuit voltage (Voc) of (0.5Volt).

Growth mechanisms of spatially separated copper dendrites in pores of a SiO2 template

n-Si/SiO2(Cu) structures with different morphologies of copper deposits are produced using the template synthesis method. Deposition of Cu nanostructures and their structural features is thoroughly studied, and mechanisms for the formation of compact and dendrite-like deposits in the pores of the SiO2 template on the n-type single-crystal silicon substrate are established. Spatially separated copper dendrites are obtained and used to investigate the efficiency of Raman scattering enhancement using the aqueous solution of the Rhodamine 6G dye.

A piezoresistive micro-accelerometer with high frequency response and low transverse effect

With the purpose of measuring vibration signals in high-speed machinery, this paper developed a piezoresistive micro-accelerometer with multi-beam structure by combining four tiny sensing beams with four suspension beams. The eight-beam (EB) structure was designed to improve the trade-off between the sensitivity and the natural frequency of piezoresistive accelerometer. Besides, the piezoresistor configuration in the sensing beams reduces the cross interference from the undesirable direction significantly. The natural frequency of the structure and the stress on the sensing beams are theoretically calculated, and then verified through finite element method (FEM). The proposed sensor is fabricated on the n-type single crystal silicon wafer and packaged for experiment. The results demonstrate that the developed device possesses a suitable characteristic in sensitivity, natural frequency and transverse effect, which allows its usage in the measuring high frequency vibration signals.

Design of a Piezoelectric Accelerometer with High Sensitivity and Low Transverse Effect.

In order to meet the requirements of cable fault detection, a new structure of piezoelectric accelerometer was designed and analyzed in detail. The structure was composed of a seismic mass, two sensitive beams, and two added beams. Then, simulations including the maximum stress, natural frequency, and output voltage were carried out. Moreover, comparisons with traditional structures of piezoelectric accelerometer were made. To verify which vibration mode is the dominant one on the acceleration and the space between the mass and glass, mode analysis and deflection analysis were carried out. Fabricated on an n-type single crystal silicon wafer, the sensor chips were wire-bonged to printed circuit boards (PCBs) and simply packaged for experiments. Finally, a vibration test was conducted. The results show that the proposed piezoelectric accelerometer has high sensitivity, low resonance frequency, and low transverse effect.

The Design and Optimization of a Highly Sensitive and Overload-Resistant Piezoresistive Pressure Sensor.

A piezoresistive pressure sensor with a beam-membrane-dual-island structure is developed for micro-pressure monitoring in the field of aviation, which requires great sensitivity and overload resistance capacity. The design, fabrication, and test of the sensor are presented in this paper. By analyzing the stress distribution of sensitive elements using the finite element method, a novel structure incorporating sensitive beams with a traditional bossed diaphragm is built up. The proposed structure proved to be advantageous in terms of high sensitivity and high overload resistance compared with the conventional bossed diaphragm and flat diaphragm structures. Curve fittings of surface stress and deflection based on ANSYS simulation results are performed to establish the sensor equations. Fabricated on an n-type single crystal silicon wafer, the sensor chips are wire-bonded to a printed circuit board (PCB) and packaged for experiments. The static and dynamic characteristics are tested and discussed. Experimental results show that the sensor has a sensitivity as high as 17.339 μV/V/Pa in the range of 500 Pa at room temperature, and a high overload resistance of 200 times overpressure. Due to the excellent performance, the sensor can be applied in measuring micro-pressure lower than 500 Pa.

Preparation and thermal-sensitive characteristic of copper doped n-type silicon material

Copper doped n-type single-crystal silicon materials are prepared by a high temperature diffusion process. The electrical and thermal-sensitive characteristic of materials is investigated under different experimental conditions. The results show that the maximum resistivity of 46.2 Ω·cm is obtained when the sample is treated at 1200 °C for 2 h with the surface concentration of the copper dopant source being 1.83 × 10−7 mol/cm2. The copper doped n-type silicon material presents a negative temperature-sensitive characteristic and the B values are about 3010–4130 K.

Preparation of colloidal lead sulfide nanoparticles by laser ablation in water for optoelectronic devices applications

In present work, lead sulfide PbS nanoparticles NPs are synthesized by laser ablation of lead sulfide target in double distilled water using 0.532 and 1.064 μm wavelengths. The transmission electron microscopy TEM, atomic force microscopy AFM and X-ray diffraction XRD were used so as to determine the shape, size, distribution, and structure of the nanoparticles prepared with different laser wavelengths. X-ray diffraction results confirmed that the lead sulfide nanoparticles crystallized in the cubic phase and presents a preferential orientation along (200) plane and with no observation of any incomplete phases. Optical band gap values of 1.9 and 2eV for the lead sulfide nanoparticles were determined by UV-Vis absorption measurements. It was found that the morphology and size of PbS NPs depend on laser wavelength. To check the possibility of synthesised nanoparticles for optoelectronic devices, a novel type of solution-processed hetero-junction photodetector, prepared by drop cast film of colloidal lead sulfide nanoparticles NPs onto n-type single crystal silicon wafer was demonstrated. The effect of laser wavelength on the electrical characteristics and photosensitivity of p-PbS/n-Si heterojunction has been investigated.

Electrical characteristics of Au/PVA (x-doped)/n-Si: Comparison study on the effect of dopant type in PVA

The main propose of this study is to investigate whether the doppant material in PVA would change the electrical characteristics of Au/PVA (X-doped) n-Si Schottky structure. Therefore, Au/PVA (Co, Zn-doped) n-Si (D1) and /PVA (Co, Ni-doped) n-Si (D2) Schottky structures were fabricated under the same condition using n-type (phosphor-doped) single crystal silicon wafer with (111) surface orientation. After the PVA/(Co-Zn) and PVA/(Co-Ni) acetates was obtained, the nanofiber film was fabricated on the silicon wafer by the use of an electrospinning technique. The results indicated that the electrical parameters of Au/PVA (x-doped) n-Si Schottky structure were significantly influenced from the doppant material in PVA. Comparative results on electrical parameters of D1 and D2 were reported in this study.

A direct evidence of fatigue damage growth inside silicon MEMS structures obtained with EBIC technique

Electron beam induced current (EBIC) is a semiconductor analysis technique performed in a scanning electron microscope (SEM) or scanning transmission electron microscope (STEM). It is able to sense defects beneath the surface even invisible by SEM. This paper presents the results of a trial to observe the defect growth inside silicon MEMS structures under fatigue loading by applying EBIC technique. The tests were performed on two specimens fabricated from an n-type single crystal silicon wafer. While the test region of the specimens was repeatedly subjected to compressive stress, EBIC images were obtained to visualize damage evolution which presented by the growth of the dark region on EBIC images. It was proved that the damage is not due to the growth of oxidation layer on the surface of the specimens but due to the growth of intrinsic defects of silicon crystal. The results would be evidences to elucidate that the fatigue damages grow inside silicon MEMS structures but not in oxidation layer.

Preparation of a silicon heterojunction photodetector from colloidal indium oxide nanoparticles

A colloidal indium oxide (In2O3) nanoparticles (NPs) were synthesized by using a Q-switched Nd:YAG laser ablation of indium target in water at room temperature. Optical absorption and x-ray diffraction (XRD) investigation of the prepared samples confirm the formation of In2O3 NPs. A solution-processed silicon heterojunction photodetector, fabricated by drop cast film of colloidal In2O3 NPs onto n-type single crystal silicon wafer, is demonstrated. I–V characteristics of In2O3 NPs/Si heterojunction under dark and illumination conditions confirmed the rectifying behavior and the good photoresponse. The built-in-voltage was determined from the C–V measurements which revealed an abrupt junction.

A high-performance multi-beam microaccelerometer for vibration monitoring in intelligent manufacturing equipment

A piezoresistive microaccelerometer with multi-beam structure is developed for vibration monitoring in intelligent manufacturing equipment. The proposed accelerometer provides a promising solution to the trade-off between the cost-effective development and demands on high-performance sensors. By incorporating tiny sensing beams, the multi-beam accelerometer obtains a higher resonant frequency and favorable measurement sensitivity compared with the quad-beam one. Theoretical analysis and finite element method (FEM) simulation demonstrate satisfactory results of an improved resonant frequency increased by a factor of 1.81 at the expense of slight sensitivity loss. Fabricated on an n-type single crystal silicon wafer, the sensor chips with multi-beam structure and quad-beam structure are wire-bonded to printed circuit boards (PCBs) and simply packaged for experiments. The static and dynamic characteristics of the two types of sensors are tested and compared. The temperature coefficient of offset output is also measured. The results show that the developed accelerometer has favorable features that allow its usage in the demanding application.