Electrical Properties Of Silicon Research Articles

The Effect of Thermal Annealing on the Electrophysical Properties of Samples n-Si<Ni,Сu>

This paper presents the results of studies of the effect of isothermal annealing at temperatures T = 673¸1473 K in the time interval 5¸60 minutes on the electrical properties of silicon, simultaneously alloyed with nickel and copper. Samples of n-Si<Ni,Cu> were obtained on the basis of the starting material - single-crystal silicon, grown by the Czochralski method with the initial resistivity r = 0.3 Ohm×cm. Diffusion was carried out at a temperature of 1523 K for 2 hours. After that, the samples were cooled at a rate of 0.1 K/s. The morphological parameters of impurity nickel and copper atom clusters formed in the bulk of silicon were measured by electron probe microanalysis on a modern Superprobe JXA-8800R setup. As it turned out, in the volume of n-Si<Ni,Cu> samples, clusters of impurity atoms with different geometric shapes are formed, the sizes of which reach up to 500 nm. The electrical properties of the samples were studied by the Hall effect method using an Ecopia HMS-7000 instrument. It was revealed that under the influence of thermal annealing (TA) at T≥1273 K, impurity clusters decompose, which leads to an increase in the resistivity of n‑Si<Ni,Cu> samples. After exposure to TA at Т=1273 K for 15 minutes, the density of impurity nanoaccumulations of acicular and lenticular shapes sharply decreases in the sample volume. Under the influence of TA at T = 1473 K for 10 minutes in the volume of the sample, the decay of impurity nanoclusters with a spherical shape is observed. Also presented are the results of changes in the density of impurity clusters, as well as structural analyzes of the samples before and after exposure to thermal annealing.

Changes in electrical properties and conduction mechanisms of Pd/n-Si diodes due to niobium dopant

A change in electrical properties of silicon (Si) diodes due to niobium (Nb) doping was studied using current–voltage (I-V) and capacitance–voltage (C-V) techniques. The observed ohmic I-V behaviour and a low-voltage capacitance peak on Nb-doped Si diodes indicated that a charge distribution mechanism has been changed and dominated by generation-recombination defect centres in the material. These Nb-induced defect centres are responsible for a reduction in free majority carrier density in the space charge region as a result of charge compensation hence an increase in material resistivity. An increase in material resistivity is confirmed by relatively high series and shunt resistances evaluated on Nb-doped Si diodes. Furthermore, the effects of Nb doping on other diode parameters such as the saturation current, Schottky barrier height, ideality factor and doping density were investigated in the study. Since the observed diode property changes are similar to those induced by promising dopants for silicon radiation-hardness, the results presented here would, therefore, assist in a quest to improve radiation-hardness of silicon by defect-engineering strategy.

Electrical Properties of Silicon Doped with Manganese via High-Temperature Diffusion

Electrical Properties of Silicon Doped with Manganese via High-Temperature Diffusion

Heat and charge transport in bulk semiconductors with interstitial defects

Interstitial defects are inevitably present in doped semiconductors that enable modern-day electronic, optoelectronic or thermoelectric technologies. Understanding of stability of interstitials and their bonding mechanisms in the silicon lattice was accomplished only recently with the advent of first-principles modeling techniques, supported by powerful experimental methods. However, much less attention has been paid to the effect of different naturally occurring interstitials on the thermal and electrical properties of silicon. In this work, we present a systematic study of the variability of heat and charge transport properties of bulk silicon, in the presence of randomly distributed interstitial defects (Si, Ge, C and Li). We find through atomistic lattice dynamics and molecular dynamics modeling studies that, interstitial defects scatter heat-carrying phonons to suppress thermal transport-1.56% of randomly distributed Ge and Li interstitials reduce the thermal conductivity of silicon by $\sim$ 30 and 34 times, respectively. Using first principles density functional theory and semi-classical Boltzmann transport theory, we compute electronic transport coefficients of bulk Si with 1.56% Ge, C, Si and Li interstitials, in hexagonal, tetrahedral, split-interstitial and bond-centered sites. We demonstrate that hexagonal-Si and hexagonal-Ge interstitials minimally impact charge transport. To complete the study, we predict the thermoelectric property of an experimentally realizable bulk Si sample that contains Ge interstitials in different symmetry sites. Our research establishes a direct relationship between the variability of structures dictated by fabrication processes and heat and charge transport properties of silicon. The relationship provides guidance to accurately estimate performance of Si-based materials for various technological applications.

Impurity State of Transition Group Elements in the Silicon Lattice in the Process of Their Interaction with Sulfur

On the basis of comparative analysis of electrical properties of silicon doped with sulfur and nickel respectively at temperature range of 1000-1250°C in 50°C increments and after their subsequent thermal annealing at temperature range of 400-950°C together with control samples of silicon doped with sulfur and nickel, it was revealed that impurity centers of sulfur and nickel do not interact with each other in the matrix of silicon. The absence of such interaction is possibly due to the fact that the electronic configuration of the impurity centers of nickel in the crystal lattice of silicon turns out to be in the filled 3d10 state, which gives it the character of an inert gas. In view of the absence of interaction of sulfur and nickel in silicon, it is concluded that electrically neutral chemically bound complexes in silicon are formed between sulfur substitution centers and centers of transition metal atoms.

Hybrid-Functional Calculations of the Copper Impurity in Silicon

Unsurprisingly, considering its significance to electronics, the impact of copper impurities on the electrical properties of silicon has been widely studied. Surprisingly, there is still marked disagreement, both among and between experiments and calculations. The remarkable disagreement between various theoretical studies is mainly due to the band-gap error in basic versions of density functional theory. This study revisits the problem using the nuanced HSE06 hybrid functional. Its model for the electronic structure of Cu in Si yields results that agree well with experimental transition levels and solubilities.

The electrophotonic silicon biosensor.

The emergence of personalized and stratified medicine requires label-free, low-cost diagnostic technology capable of monitoring multiple disease biomarkers in parallel. Silicon photonic biosensors combine high-sensitivity analysis with scalable, low-cost manufacturing, but they tend to measure only a single biomarker and provide no information about their (bio)chemical activity. Here we introduce an electrochemical silicon photonic sensor capable of highly sensitive and multiparameter profiling of biomarkers. Our electrophotonic technology consists of microring resonators optimally n-doped to support high Q resonances alongside electrochemical processes in situ. The inclusion of electrochemical control enables site-selective immobilization of different biomolecules on individual microrings within a sensor array. The combination of photonic and electrochemical characterization also provides additional quantitative information and unique insight into chemical reactivity that is unavailable with photonic detection alone. By exploiting both the photonic and the electrical properties of silicon, the sensor opens new modalities for sensing on the microscale.

Impact of Copper-Doped Titanium Dioxide Interfacial Layers on the Interface-State and Electrical Properties of Si-based MOS Devices

The current study presents the interface-state and electrical properties of silicon (Si)-based metal-oxide-semiconductor (MOS) devices using copper-doped titanium dioxide (Cu:TiO2) nanoparticles for possible applications as an interfacial layer in scaled high-k/metal gate MOSFET technology. The structural properties of the Cu:TiO2 nanoparticles have been obtained by means of X-ray diffraction (XRD), UV–Vis–NIR spectrometry, atomic force microscopy, and scanning electron microscopy measurements; they were compared with pure TiO2 thin film. With the incorporation of Cu, rutile-dominated anatase/rutile multiphase crystalline was revealed by XRD analysis. To understand the nature of this structure, the electronic parameters controlling the device performance were calculated using current–voltage (I–V), capacitance–voltage (C–V), and conductance–voltage (G–V) measurements. The ideality factor (n) was 1.21 for the Al/Cu:TiO2/p-Si MOS device, while the barrier height ϕb was 0.75 eV with semi-log I–V characteristics. This is in good agreement with 0.78 eV measured by the Norde model. Possible reasons for the deviation of the ideality factor from unity have been addressed. From the C–V measurements, the values of diffusion potential, barrier height, and carrier concentration were extracted as 0.67, 0.98 eV, and 8.73 × 1013 cm−3, respectively. Our results encourage further work to develop process steps that would allow the Cu-doped TiO2 film/Si interface to play a major role in microelectronic applications.

Formation of Copper Impurity-Defect Complexes and Their Impact on Electrical Properties of Silicon

Nature and types of structural defects in the p-type silicon doped with copper are determined by the methods of infrared microscopy and measuring of the specific resistivity, concentration, and lifetime (τ) of charge carriers. It is found that the value of τ is increased and stabilized due to the formation of a trap level associated with the “copper-oxygen” complex [Cu-O] in silicon. It is shown that the copper atoms migrate from a saturated dislocation to the volume of lightly doped silicon during slow cooling after high-temperature diffusion, which is associated with the decomposition of the Si–Cu solid solution.

Irradiation Enhancement of Electrical Properties of Passive Impurities in Silicon Crystals

Radiation defect formation processes in silicon crystals for the cases when concentrations of electrical nonactive impurities (oxygen, carbon) prevail over main impurities determining siliconconductivity, are being covered in this paper. The role of interstitial atoms and vacancies, oxygen and impurity atoms in formation of radiation defects of A - and E-centers and divacancies, as well as their influence on electrical and optical properties ofsilicon crystals are shown. Energy levels of radiation defects in forbidden gap of silicon and their introduction rates were defined based on temperature dependencies of the concentrations of charge carriers at different irradiation doses. The capture probability of interstitial atoms and vacancies by main and passive impurities is taking into account. In addition to known A -and E-centers, along with disordered regions (clusters), a new radiation centers with energetic levels at

Effect of the trench shape on the electrical properties of silicon based trench barrier schottky diode

With the globally enhancing demand for the energy saving and environmental protection of electronic products, the requirement for Schottky diode which is widely used in electronic products becomes higher and higher. The trench metal-oxide-semiconductor barrier Schottky (TMBS) diode is more and more favored because of its excellent performance. The shape of the trench plays an important role in determining the electrical properties of the Schottky diode. However, there is no intensive study on this point. In this study, we propose two novel trench structures, i. e., filleted corner trench and ladder trench. By performing the simulation with Medici, it is found that compared with the traditional trench TMBS diode, the filleted corner trench TMBS diode has a breakdown voltage with 15.8% increase under the conditions of the same leakage current and the forward turn-on voltage. Also, the ladder trench TMBS diode can reduce the leakage current by 35%, while have a breakdown voltage not smaller than the right angle trench TMBS and a forward turn-on voltage only a little bit higher than the right angle trench TMBS.

Effect of a weak magnetic field on the micromechanical and electrical properties of silicon for use in solar power engineering

The effect of a dc magnetic field (0.17 T) on the microhardness and photoconductivity decay kinetics in silicon crystals used in solar power engineering is studied. Variations in the micromechanical and electrical properties in the samples under study are considered to be functions of the time after completing the magnetic treatment. The results are discussed from the standpoint of magnetic-field-enhanced processes in a subsystem of structural defects.

Effects of low-temperature annealing phosphorous gettering process on the electrical properties of multi-crystalline silicon with a low minority carrier lifetime

A new low-temperature annealing phosphorous gettering process (LTAPGP) was developed to improve the electrical properties of multi-crystalline silicon which has a low minority carrier lifetime. LTAPGP combined a multi-plateau temperature phosphorous gettering process and a low-temperature annealing process. LTAPGP can remove the iron impurities and crystallographic defects of multi-crystalline silicon, and improve the electrical properties of silicon solar cells that were produced from low minority carrier lifetime silicon wafers. Compared with multi-plateau and two-plateau temperature phosphorous gettering process, LTAPGP was more effective in gettering iron impurities and repairing crystallographic defects. The multi-crystalline silicon wafers with a low minority carrier lifetime went through an LTAPGP process were utilized to produce solar cells. The IV-measurement data prove that the efficiency of the new solar cells is 0.2% higher than that of specimens subject to the multi-plateau and two-plateau temperature processes. The results indicat that LTAPGP can make the low minority carrier lifetime silicon wafers to be used in solar cell industry, improve the utilization ratio and reduce the production cost of cast polysilicon.

Comparative study of changes in electrical properties of silicon and silicon carbide upon proton irradiation

Rates of carrier removal from the conduction band in n-type FZ-Si and 4H-SiC irradiated with 8- and 15-MeV protons at room temperature are discussed. Calculated rates of formation of primary radiation defects (Frenkel pairs) in these materials are presented and compared with the corresponding experimental values. Protons create defects in collision cascades involving recoil atoms formed in the crystal lattice itself. The results are compared with similar data previously obtained in irradiation of n-type FZ-Si and 4H-SiC with 900-keV electrons, in which case isolated so-called close Frenkel pairs are absolutely dominant among primary radiation defects. It has been found that the E-center model adequately describing the decrease in the electrical conductivity of n-FZ-Si upon electron irradiation is inapplicable to interpretation of experimental data for proton-irradiated materials. It is suggested that a pronounced annealing of “simple” radiation defects of the type of close Frenkel pairs occurs during irradiation at room temperature.

Low Temperature Growth of Silicon Structures for Application in Flash Memory Devices

AbstractAn in-depth study of the structural and electrical properties of silicon (Si) films deposited by a novel low temperature technique at temperatures less than 400°C in a 13.56 MHz RF PECVD reactor is reported. The method is based on substrates having to undergo some initial preparatory steps (IPS) before the deposition of Si films in the PECVD chamber. The optical band gap of Si films deposited using this novel technique narrowed to 1.25 eV from 1.78 eV using the traditional a-Si:H deposition recipe. No annealing of any form was performed on the films to attain this band gap. Furthermore, photosensitivities for these films under various deposition conditions were of order 100 compared to 104 for a-Si:H films deposited under like conditions. Using metal-insulator-semiconductor devices, the Si films grown by this novel technique exhibit charge storage and memory behaviour unlike their amorphous counterparts. However, device endurance has been found to be inadequate, probably due to the presence of some contaminants - notably interstitial oxygen - which has been found elsewhere to have adverse effects on the electrical characteristics of Si films. If well harnessed, we suggest Si structures grown by this novel growth technique could be well-suited for flash memory applications, particularly 3-D flash which requires process temperatures to be less than 400 °C.

Electrical Properties of Silicon with Bistable Impurity Complexes

AbstractMany impurity complexes in silicon such as boron-oxygen and iron-boron complexes are found to be bistable. Commonly bistable recombinative complexes in silicon are studied through carrier lifetime experiments and are analysed by use of Shockley-Read-Hall (SRH) recombination theory. SRH recombination theory is valid for stable defects with one configuration and one energy level in the band gap, however, the theory might fail upon considering the recombination centers through bistable defects, which can be in two different configurations separated by a potential barrier. This work presents a study of electrical properties of silicon with bistable impurity complexes. The analysis has been performed for statistics of free electrons and holes, their recombination rate and lifetime. The results have been compared with those obtained from the Shockley-Read-Hall recombination theory.

Non-Contact Cleaning Process for Post-CMP Copper

Introduction Cleaning is required following CMP (chemical mechanical planarization) to remove particles as well as metallic and organic contamination. Particle and contamination requirements tighten with each successive technology generation, and the cleaning of wafers becomes more complicated and more critical [1]. Smaller size particles must be removed from the wafer surface as linewidths decrease while lower and lower contamination levels must be achieved as device electrical parameters tighten. Metal contamination on the dielectric surface may cause dielectric leakage and any metals that affect the electrical properties of silicon must be removed from the surface. In addition, constraints on the aggressive nature of the cleaning process are increased. For example, the amount of material removed in the cleaning process and the resulting surface roughness must be precisely controlled.

Silicon bronze alloy

In this chapter, properties of silicon are explained in detail. Silicon is an abundant element found in the Earth’s crust in various compounds. Semiconductor and MEMS applications use annually more than 40,000 tons of high-purity silicon. Quartz or silicon dioxide, is the most common starting raw material for purified silicon for semiconductor and sensor applications, and the Siemens process is the most commonly used in semiconductor-grade silicon production. Silicon crystallizes into a diamond cubic crystal structure in which the atoms are covalently bonded. Silicon is a hard, brittle material, and at room temperature under stress silicon single crystal elongates elastically until fracture stress appears without significant plastic deformation. Silicon is a group IV element in the periodic table and is a semiconductor with a bandgap of 1.12 eV, which means that pure silicon at room temperature is almost an insulator. By doping with group III or group V elements, the resistivity of silicon can be varied over a wide range. In this chapter, mechanical and electrical properties of silicon are explained in detailed. Schematic diagrams help to better understand the reaction of silicon and its various properties.

Electrical properties of silicon layers implanted with erbium and oxygen ions in a wide dose range and thermally treated in different temperature conditions

The electrical properties of silicon implanted with Er and O ions in a wide dose range have been studied. The dependence of electron mobility on the concentration of electrically active centers is determined for Si:Er layers with Er concentrations in the range of 9×1015–8×1016 cm−3. Sharp bends related to specific features of Er segregation in solid-phase epitaxial recrystallization are observed in the concentration profiles of electrically active centers, n(x), and Er atoms, C(x), at Er ion implantation doses exceeding the amorphization threshold. The n(x) and C(x) profiles virtually coincide near the surface. A linear rise in the maximum concentration of electrically active centers at approximately constant effective coefficient of their activation, k, is observed at Er implantation doses exceeding the amorphization threshold. At an Er concentration higher than 7×1019 cm−3, the concentration of electrically active centers levels off and k decreases.

Electrical properties of silicon- and beryllium-doped GaInP and (AlGa)InP grown by solid source molecular beam epitaxy

Abstract Silicon- and beryllium-doped Ga0.52In0.48P and (Al0.7Ga0.3)0.52In0.48P were grown by solid source molecular beam epitaxy using a valved phosphorus cracker cell. The electrical properties were investigated using van der Pauw–Hall and capacitance–voltage measurements at room temperature. The highest electron concentration obtained was 6.9×1018 and 2.1×1018 cm−3 for Silicon doped Ga0.52In0.48P and (Al0.7Ga0.3)0.52In0.48P, respectively. The highest hole concentration obtained was 1.1×1019 and 4.9×1018 cm−3 for beryllium-doped Ga0.52In0.48P and (Al0.7-Ga0.3)0.52In0.48P, respectively. The Hall electron mobilities of Si-Ga0.52In0.48P and Si-(Al0.7Ga0.3)0.52In0.48P within the carrier concentration range of 1017