Phosphorus Doping Research Articles

New Process Integration of Sequential Phosphorus-Doped Silicon for Trench Field Plate Power MOSFETs

In advanced field plate trench power MOSFETs (FP-MOSFETs), narrow and deep trench causes lots of challenges for process integration. Especially, process optimization for silicon in trench is the most crucial. Sequential phosphorus doping process is expected to form decent silicon electrodes in narrow and deep trenches. Therefore, we studied new process optimization of FP-MOSFETs with sequential phosphorus-doped silicon method, compared with “conventional” phosphorus diffusion method. We succeeded in reducing processing variations in field plates and decreasing wafer warpage by processing phosphorus-doped silicon without activation annealing. Inserting 800 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> C annealing before 1000 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> C annealing contributed no voids in silicon field plates and gates. In addition, good electrical characteristics was demonstrated with the optimized process.

Fabrication of pn junction arrays with highly successful grown n-Si microneedles by using low temperature VLS method

Arrays of pn junctions have been fabricated with n-Si microneedles. In situ doping vapor–liquid–solid (VLS) growth has been carried out with p-Si substrate having metallic catalyst (Au) dots on its surface, using Si2H6 and PH3 for supplying Si and phosphorus to fabricate n-Si microneedles on the surface of p-Si substrate in vertical direction; thus, pn junctions have been fabricated at microneedle-substrate interface. These n-Si microneedles have been grown at the temperature of 680 °C, which is about 420 °C less than the temperature (at least 1100 °C) required by conventional diffusion method of doping. In this work, n-Si microneedles have been successfully fabricated with 100% yield, the highest success ever for n-type VLS growth in micro range. The position and size of these n-Si microneedles are controllable. These n-Si microneedles are highly conductive. Physical and electrical characteristics of n-Si microneedles have been investigated by varying Au dot size and the level of phosphorus doping. The properties of interface pn junction have been investigated and compared with standard diode characteristics and theoretical results. Highly conductive n-Si microneedle arrays, embedded with interface pn junctions, might be used for collecting and processing bio-signals, profiling temperature/pressure inside living cells and many other sensor applications.

Amorphous phase induced high phosphorous-doping in dandelion-like cobalt sulfides for enhanced battery-supercapacitor hybrid device

Abstract Phosphorus (P) doping is considered to be an effective method for regulating the physicochemical properties of transition metal sulfides (TMSs) through triggering lattice distortion, improving electronic conductivity, and providing additional active sites for charge storage. However, the large P atom makes it difficult to be incorporated in TMSs, particularly at high doping level. Herein, we develop an amorphous phase induced strategy for efficient P doping in dandelion-like cobalt sulfides, reaching a high concentration of 18 at%. The obtained P-CoS1.097-6 displays remarkable specific capacity of 536 C g−1 and 502 C g−1 at the current density of 5 A g−1 and 20 A g−1, respectively, due to the enhanced electrical conductivity and rapid ion diffusion. This performance is higher than that of P-CoS1.097-48 with a low doping level of 7 at% (400 C g−1), the primeval Co1−xS-6 (345 C g−1), and CoS1.097-48 (335 C g−1). Based on P-CoS1.097-6 and activated carbon, the battery-supercapacitor hybrid (BSH) device delivers an electrochemical performance of 22 Wh kg−1 (energy density) and good stability with 88% capacity retained over 6000 cycles.

Nitrogen and phosphorus dual-doped porous carbons for high-rate potassium ion batteries

Pitch-based porous carbons with the abundant resources and high conductivity have potential advantages as potassium-ion battery anode materials. However, they suffer from small interlayer distance and rare potassium storage sites. Herein, nitrogen and phosphorus dual-doped coal tar pitch-based porous carbons (NPPC) was prepared in one-step carbonization using ammonium polyphosphate as N and P source and studied as the anodes for the potassium ion batteries. NPPC delivers a high capacity retention of 81.8% over 400 cycles at 1.0 A g−1. When the current density is raised to 10 A g−1, it can still retain a reversible capacity of 126 mAh g−1. The effects of carbonation temperature and ratio of ammonium polyphosphate to coal tar pitch on nitrogen and phosphorus doping contents were investigated by in situ Fourier transform infrared and synchronous thermal analysis. This work may shed light on the design of advanced potassium-ion battery by employing heteroatom doped functionalized soft carbons.

Phosphorus-Doped Metal-Organic Framework-Derived CoS2 Nanoboxes with Improved Adsorption-Catalysis Effect for Li-S Batteries.

Lithium-sulfur (Li-S) batteries are regarded as one of the most promising next-generation battery technologies owing to their ultrahigh energy density up to 2600 W h kg-1 and low cost. However, major challenges still remain in the application of Li-S batteries, such as shuttle effect and sluggish redox kinetics. Herein, it is demonstrated that phosphorus doping can not only significantly improve the polysulfide adsorption but also enhance the catalysis effects of metal-organic framework-derived CoS2 nanoboxes in Li-S batteries. Consequently, a modified separator integrated with P-CoS2 and carbon nanotubes effectively suppresses the polysulfide shuttle and propels the redox kinetics of polysulfides, thus promising higher specific discharge capacity, better rate, and stable cycle performance. Even under the high sulfur loading condition (4.8 mg cm-2), the areal discharge capacity of the cell with the functional separator can still remain at 4.5 mA h cm-2 after 100 cycles at 0.2 C. More importantly, this work may encourage more effort on anion doping for engineering the polar surface of transition-metal compounds to further mediate the interfacial redox chemistry between transition-metal compounds and polysulfides in Li-S batteries.

Phosphorus-doped Carbon Nitride Nanosheets as Efficient White-LED-Light-Driven Photocatalyst for Hydrogen Evolution and Tetracycline Degradation

g-C3N4 has received much attention due to its role in photocatalytic hydrogen evolution and contaminants degradation. Nevertheless, the photocatalytic property of bulk g-C3N4 (BCN) is seriously restricted owing to its short photo-generated carrier lifetime, small specific surface area and low visible light utilization rate, etc. In this study, nanosheet constructing and heteroatom phosphorus (P) doping, as two important strategies, are synergistically adopted to co-enhance its activity. The controllable P atoms were successfully doped into the framework of g-C3N4 nanosheet (NCN-P) through forming P-N bond. The optimized NCN-P sample displays an excellent H2 production rate (3263.99 µmol·g−1·h−1) under white LED light irradiation, which is more than 11.6 times that of the BCN. Moreover, it also exhibits excellent photocatalytic degradation ratio of tetracycline reached 80% in 1 h. Furthermore, the optimized NCN-P sample still maintains robust photocatalytic performance after recycling tests, making it as a bright prospect photocatalyst for solar energy utilization and contaminants removal.

Atomistic insights into lithium adsorption and migration on phosphorus‐doped graphene

AbstractWe present a comprehensive density functional theory study of the effects of phosphorus doping of graphene on adsorption and diffusion behavior of lithium. We find that protrusion introduced by phosphorus doping enhances the adsorption of a single lithium atom onto graphene due to an additional partial covalent bonding between lithium and carbon atoms of the substrate. With an increase in concentration of lithium atoms, cluster formation is observed near the phosphorus dopant. Finite density of states at Fermi level indicates the electronic conductivity of phosphorus‐doped graphene before and after the adsorption of a lithium atom. An increase in density of states above the Fermi level is observed with increased lithium concentration. The protrusions caused by phosphorus dopants act as trapping centers for lithium, thereby hindering their migration over the substrate. This atomic level study can act as a guideline for further development of electrode materials for novel battery technologies.

Phosphorus in honeycomb-like carbon as a cathode boosting pseudocapacitive properties for Zn-ion storage

Zn-ion hybrid supercapacitors (ZSCs) are an advanced energy storage device displaying promising prospects with battery-type and capacitive electrodes. Unveiling the reaction paths of dopants in carbon cathode is essential for rationally improving deficient adsorption sites to match the high energy capacity of Zn anode. In this work, the P-doped honeycomb-like porous carbon with abundant micro/mesoporous channels is employed as a cathode for ZSCs. Phosphorus dopant could significantly enhance pseudo-capacitance by promoting the reaction of the oxygen functional groups and Zn ions, but does not participate in pseudo-capacitance reactions. The P-doped honeycomb-like porous carbon exhibits interconnected conductive network and abundant electroactive sites. The resulting ZSCs devices deliver an energy density of 129.3 Wh/kg at a power density of 1000 W/kg and 72.54 Wh/kg even at the high power density of 20000 W/kg as well as excelling cycling life over 10,000 cycles.

Tuning the electronic and magnetic properties of graphene nanoribbons through phosphorus doping and functionalization

Phosphorus-doped carbon materials are a promising candidate for energy storage devices, water splitting, molecular sensing, spin filtering, and optical quantum computers. We investigated the incorporation of phosphorus in pristine and defected graphene nanoribbons (GNRs) using first-principles density functional theory calculations. We analyzed how P-doping and P-functionalities modify the structure and electronic and magnetic properties of GNRs having armchair (AGNRs) and zigzag (ZGNRs) edges. The functional groups were anchored at the edges of the GNRs. The results were analyzed for band structure, the density of states, charge transfer, wave functions, spin density, oxidation energies, and protonation energies. Our findings revealed that the incorporation of phosphorous into the graphitic structures promotes p-type doping. P-doping and P-functionalization in graphene nanoribbons induced a bandgap reduction. Metallic behavior was found for phosphole-like doping (P in a pentagonal ring), P-2vac configuration (P replacing two vacancies), phosphoramide, and phosphorus-dithiolate. The magnetic properties of ZGNRs were strongly influenced by phosphorus doping and functionalization. Usually, the P-doping in ZGNRs promotes a ferromagnetic ground state with aligned spins at the edges and a total magnetization ranging in 3.18–3.90 μB. AGNRs functionalized with phosphate, phosphite, and phosphorodithiolate groups exhibited a ferromagnetic ground state with magnetic moments localized at the functional groups with a total magnetization of 1.03–1.33 μB. The energetic stability of the magnetic properties is discussed. From protonation and oxidation energy calculations, Phosphorus-doping edges (phosphole-like and phosphine-like) are more susceptible to trap H or O atoms. The ribbon width dependence of the total magnetization and protonation energy for phosphate and phosphite functional groups are also discussed. The results obtained from this investigation provide a theoretical basis for better understanding experimental evidence of ferromagnetism in phosphorus-doped graphene and chemical activity of phosphorus-doped graphitic materials. Our investigations propose possible scenarios on the magnetism source in recent experimental findings on ferromagnetism in P-doped graphene and provide a theoretical basis to understand the phosphorus further into graphitic materials.

Promoting the electrocatalytic activity of platinum film for hydrogen evolution reaction by phosphorus doping

The electrocatalytic performance of platinum film for HER is improved through phosphorus (P) doping. Platinum (Pt) and platinum-phosphorus (Pt–P) films are conveniently prepared on copper substrates through a modified electroless deposition strategy. The P doping, which is confirmed by EDS and XPS tests, can reduce the crystallinity of Pt and affect the electronic environment of Pt in the Pt–P film. Compared to the Pt film, the Pt–P film shows better electrocatalytic activity and stability for HER in 1.0 M KOH solution. The Pt–P film has the overpotential of 87.8 mV at a current density of 10 mA cm−2, far below the Pt film with the corresponding overpotential of 254 mV.

On the Enhanced Phosphorus Doping of Nanotextured Black Silicon

The integration of nanotextured black silicon (B-Si) into solar cells is often complicated by its enhanced phosphorus doping effect, which is typically attributed to increased surface area. In this article, we show that B-Si's surface-to-volume ratio, or specific surface area (SSA), which is directly related to surface reactivity, is a better indicator of reduced sheet resistance. We investigate six B-Si conditions with varying dimensions based on two morphology types prepared using metal-catalyzed chemical etching and reactive-ion etching. We demonstrate that for a POCl3 diffusion, B-Si sheet resistance decreases with increasing SSA, regardless of surface area. 2-D dopant contrast imaging of different textures with similar surface areas also indicates that the extent of doping is enhanced with increasing SSA. 3-D diffusion simulations of nanocones show that both the extent of radial doping within a texture feature and the metallurgical junction depth in the underlying substrate increase with increasing SSA. We suggest SSA should be considered more readily when studying B-Si and its integration into solar cells.

Role of Deposition Pressure on Properties of Phosphorus Doped Hydrogenated Nano-Crystalline Silicon (nc-Si:H) Thin Films Prepared by the Cat-CVD Method

Objective: Phosphorus doped hydrogenated nano-crystalline silicon (nc-Si:H) thin films were synthesized by catalytic chemical vapor deposition (Cat-CVD) method. Methods: The effect of deposition pressure on opto-electronic and structural properties was studied using various analysis techniques such as low angle XRD analysis, FTIR spectroscopy, Raman spectroscopy, UV-Visible spectroscopy, dark conductivity, etc. Results: From low angle XRD and Raman spectroscopy analysis, it is observed that an increase in deposition pressure causes Si:H films to transform and transit from amorphous to the crystalline phase. At optimized deposition pressure (300 mTorr), phosphorous doped nc- Si:H films having a crystallite size of ∼29 nm and crystalline volume fraction of ∼58% along with high deposition rate (∼29.7 Å/s) have been obtained. The band gap was found to be ∼1.98 eV and hydrogen content was as low as (∼1.72 at. %) for these films. Conclusion: The deposited films can be useful as an n-type layer for Si:H based p-i-n, tandem and c-Si hetero-junction solar cells.

Synthesis of metal-free phosphorus doped graphitic carbon nitride-P25 (TiO2) composite: Characterization, cyclic voltammetry and photocatalytic hydrogen evolution

Herein, the improved visible-light photocatalytic activity towards efficient hydrogen generation using modified P25 (TiO2) has been demonstrated. The P25 has been modified with pure and Phosphorus doped graphitic carbon nitride (CN and PCN) successfully and well-characterized by several analytical techniques. The effect of Phosphorus doping in CN favours to tune the opto-electronic and textural properties. The optimized composite of CN–P25 and PCN–P25 shows nearly twenty-two-fold (920 μmol/g) and forty-fold (2531 μmol/g) enhancement in hydrogen production as compared to CN and PCN respectively and nearly ten-fold and twenty-five-fold enhancement in hydrogen production as compared to P25. This overwhelming enhancement in hydrogen production can be attributed to the lowering of the conduction band by 0.13 eV and small conduction band offset of 0.35 eV estimated by cyclic voltammetry, which provokes the electron-hole recombination and better charge transfer at the PCN–P25 interface. These results unlock great avenues to develop the low cost and metal-free photocatalyst by simply modifying P25 with PCN in the field of energy and clean environment.

Photo-generated charges escape from P+ center through the chemical bridges between P-doped g-C3N4 and RuxP nanoparticles to enhance the photocatalytic hydrogen evolution

Many researches have shown that phosphorus doping can affect the photocatalytic activity, mainly because the incorporation of P atoms significantly alters the electronic, surface chemical, and properties of different semiconductors. However, excessive phosphorous doping will form the accumulation and recombination center of photo-generated charge carrier, thereby limiting the activity of photocatalytic reactions. In this work, we successfully prepared excessive P-doping g-C3N4 with ruthenium phosphide nanoparticles (RuxP/PCN), which had excellent performance of hydrogen evolution (1.94 mmol g−1 h−1). Specifically, C was replaced by P in the melon units of PCN and positive charge center (P+) was introduced, reinforcing the chemical connection between PCN and RuxP. In fact, excessive P+ centers became the traps and stacking centers of photo-generated carriers. However, due to the introduction of RuxP NPs, the accumulated charges in the P+ centers through the chemical bridges between PCN and RuxP NPs migrated to surface and then separated on RuxP NPs. Our research illustrates the mechanism of the accumulated charges caused by excessive phosphorus doping migrate to the surface and separate on phosphides, which can prolong the lifetime of photo-generated carriers. This result promoted the significant increase of photocatalytic hydrogen production activity. Our research clarifies the mechanism of excessive phosphorus doping and phosphides act on this photocatalytic system, which will provide a new way to design a photocatalytic system with higher HER performance.

Nanocluster PtNiP supported on graphene as an efficient electrocatalyst for methanol oxidation reaction

In this study, phosphorus doped graphene supported PtNiP nanocluster electrocatalyst (PtNiP/P-graphene) was successfully prepared via a simple hypophosphite-assisted co-reduction method. The improved anchoring force and increased anchoring sites of graphene support result from phosphorus doping as well as size-confined growth effect of NaH2PO2 leads to uniform dispersion of ultrafine PtNiP nanoclusters. Doped P also promotes the removal of CO-like intermediate by adjusting Pt electronic structure combining with alloyed Ni via electronic effects. As a result, the as-prepared PtNiP/P-graphene catalyst with more exposed active sites and optimized electronic structure of Pt alloy shows excellent electrocatalytic performances for methanol oxidation reaction (MOR) both in activity and durability in an acidic medium.

Novel phosphorus-doped Bi2WO6 monolayer with oxygen vacancies for superior photocatalytic water detoxication and nitrogen fixation performance

Chemical phosphorus doping has recently regarded as an effective method for band gap and charge transfer kinetics regulation of semiconductor photocatalysts. However, few more P-doped photocatalysts are investigated except TiO2 and g-C3N4 systems up to now. Herein, a novel phosphorus-doped Bi2WO6 (PBWO) monolayer with oxygen vacancies was successfully synthesized through a facile one-step hydrothermal treatment using elemental red phosphorus (RP) as P source. Particularly, P atoms were doped into the lattice of Bi2WO6 in [BiO]+ layers via forming Bi-O-P bonds, and rich oxygen vacancies were introduced by phosphorus doping process. The optimized PBWO sample exhibits a remarkable visible-light photocatalytic simultaneous degradation of Cr(VI) and tetracycline hydrochloride activity, and a satisfactory photocatalytic nitrogen fixation rate of 73.6 μmol g−1 h−1 under simulated light irradiation, which is significantly enhanced compared to pristine BWO and phosphorus-containing heterostructures of BiPO4/Bi2WO6 and RP/Bi2WO6. Based on the results of various characterizations and DFT calculations, the superior photocatalytic performance of PBWO can be attributed to the synergistic effect of phosphorus doping coupled with oxygen vacancies, which improves the visible light absorption, modulates the band structure, introduces a defect level in the forbidden band, and effectively promotes the separation efficiency of photogenerated electron-hole pairs. The detailed photocatalytic mechanism was further proposed according to the radical capturing experiment and ESR technology.

Ultrasensitive and Tunable Sensor Based on Plasmon-Induced Transparency in a Black Phosphorus Metasurface

We propose an ultrasensitive and tunable mid-infrared sensor based on plasmon-induced transparency (PIT) in a monolayer black phosphorus metasurface. Results show that there are two PIT windows, each of which occurs when the long axis of the metasurface is placed along the MBP’s armchair and zigzag crystal directions, respectively. The corresponding sensors based on these PIT effects show high sensitivities of 7.62 THz/RIU and 7.36 THz/RIU. Both PIT frequencies can be tuned statically by varying the geometric parameters or dynamically by changing the electron doping of monolayer black phosphorus, making the sensors adaptable to tackle with a variety of scenarios. We expect that this work will advance the engineering of metasurfaces based on monolayer black phosphorus and promote their sensing applications.

Effect of KOH on the Energy Storage Performance of Molasses-Based Phosphorus and Nitrogen Co-Doped Carbon

In this study, we have evaluated the effect of potassium hydroxide (KOH) on the energy storage performance of metal-free carbon-based materials prepared from molasses. Molasses are a renewable-resource biomass and economical by-product of sugar refinement, used here as a carbon precursor. Two co-doped carbon materials using molasses were synthesized via a time and cost-efficient microwave carbonization process, with ammonium polyphosphate as a phosphorus and nitrogen doping agent. The phosphorus and nitrogen co-doped carbon (PNDC) samples were prepared in the presence and absence of a chemical activating agent (KOH), to study the role of chemical activation on PNDCs. Physical characterizations were performed to gain insight into the composition, pore size and topographical data of each material. Electrochemical characterization via cyclic voltammetry in 1 M sulfuric acid (H2SO4) as well as in 6 M KOH as electrolytes, revealed high current density and specific capacitance for the chemically activated material (PNDC2) compared to one without chemical activation (PNDC1). The capacitance value of 244 F/g in KOH electrolyte was obtained with PNDC2. It is concluded that addition of KOH prior to carbonization increases the surface functionality, which significantly enhances the electrochemical properties of the PNDC material such as current density, stability, and specific capacitance.

Homodispersed B–CN/P–CN S-scheme homojunction for enhanced visible-light-driven hydrogen evolution

Proper interface and band alignment always play essential roles in the separation of photoexcited charge of photocatalysts. In this work, we prepared a homodispersed S-scheme carbon nitride homojunction with local electron structure difference by a facile pre-doping and two-step calcination approach. Boron doping into heptazine created extra acceptor impurity, and phosphorus doping into heptazine created extra donor impurity, which eventually modulated the electronic structure of carbon nitride. As heptazines with different element doping were integrated into carbon nitride by recalcination, B–CN and P–CN formed a homodispersed homojunction and thus produced a rich interface. Meanwhile, caused by Fermi energy levels equilibrium, the band bending constructed an S-scheme homojunction, which stimulated photogenerated electrons to transfer from CB of B–CN to VB of P–CN. The homodispersed S-scheme homojunction structure led to efficient suppression of recombination of photoinduced charge and retained stronger redox charge. Consequently, the photocatalytic performance was dramatically boosted to 2620 μmol g−1 from 60 μmol g−1 of pure CN in 4-h hydrogen evolution from water. This novel method for electron structure engineering helped to provide a new strategy for designing homojunction photocatalysts with excellent photocatalytic performance.

Phosphorus doping of ZnO using spin‐on dopant process: A better choice than costly and destructive ion-implantation technique

Radio frequency sputtered ZnO thin films doped with phosphorus (ZnO:P) have been prepared employing spin-on dopant process. In the SOD process, the dopant film has been spin-coated on a silicon substrate and positioned close to the as-deposited undoped ZnO film at high temperature to perform the phosphorus doping. The high-resolution X-ray diffraction measurement reveals that the prepared ZnO:P films are good in crystalline quality which improves further by annealing. It is found that the full-width half-maximum corresponding to (002) peak of SOD processed thin films is much narrower than previously reported ion-implanted thin films, indicating the better crystalline quality of SOD processed phosphorus-doped ZnO thin films. The X-ray photoelectron spectroscopy measurement signifies that the P2O5 decomposes into two phosphorus atoms behaving like an acceptor dopant and five oxygen atoms which may fill in oxygen vacancies at high-temperature annealing. The photoluminescence spectra discover the acceptor bound exciton peak at 3.35 eV and free electron to acceptor level transitions at 3.31 eV. The calculated acceptor binding energy is 127 meV for the phosphorus dopant which works as a shallow acceptor level. It is found that the phosphorus-doped ZnO thin films prepared using the SOD process have much superior structural and optical properties in comparison to previously reported ion-implanted film. This study demonstrates that the SOD process is much superior than the ion-implantation process to produce high-quality ZnO:P thin films for very stable p-type conduction.