Effect Of Hydrogen Passivation Research Articles

Unveiling Hydrogen Passivation Effects in TiC-Based Single-Atom Catalysts for Enhanced Hydrogen Evolution Reaction

Unveiling Hydrogen Passivation Effects in TiC-Based Single-Atom Catalysts for Enhanced Hydrogen Evolution Reaction

Effects of different atomic passivation on conductive and dielectric properties of silicon carbide nanowires

Based on the transport and polarization relaxation theories, the effects of hydrogen, fluorine, and chlorine atom passivation on the conductivity and dielectric properties of silicon carbide nanowires (SiCNWs) were numerically simulated. The results show that passivation can decrease the dark conductivity of SiCNWs and increase its ultraviolet photoconductivity. Among them, the photoconductivity of univalent (H) passivated SiCNWs is better than that of seven-valent (Cl, F) passivated SiCNWs. In terms of dielectric properties, the passivated SiCNWs exhibit a strong dielectric response in both deep ultraviolet and microwave regions. Hydrogen passivation SiCNWs produce the strongest dielectric response in deep ultraviolet, while fluorine passivation SiCNWs produce the strongest dielectric relaxation in the microwave band, which indicates that atomic passivation SiCNWs have a wide range of applications in ultraviolet optoelectronic devices and microwave absorption and shielding.

Hydrogenation of silicon-nanocrystals-embedded silicon oxide passivating contacts

We investigate the effect of hydrogen passivation of dangling bonds in silicon oxide passivating contacts with embedded silicon nanocrystals (NAnocrystalline Transport path in Ultra-thin dielectrics for REinforced passivation contact, NATURE contact). We first investigated the differences in electrical properties of the samples after hydrogen gas annealing and hydrogen plasma treatment (HPT). The results show that the NATURE contact was efficiently passivated by hydrogen after HPT owing to the introduction of hydrogen radicals into the structure. Furthermore, we examined the dependence of process parameters such as HPT temperature, duration, and H2 pressure, on the electrical properties and hydrogen depth profiles. As a result, HPT at 500 °C, 15 min, and 0.5 Torr resulted in a large amount of hydrogen inside the NATURE contact and the highest implied open-circuit voltage of 724 mV. Contact resistivity and surface roughness hardly increased when HPT was performed under the optimized condition, which only improved the passivation performance without deteriorating the electron transport properties of the NATURE contact.

Investigation of thermoelectric properties of cadmium selenide CdnSen (n= 7, 11, 13) molecular junctions: a DFT study.

The thermoelectric properties of cadmium selenide (CdnSen) molecular junctions (n = 7, 11, 13) were investigated before and after adding hydrogen atoms. The effects of hydrogen passivation on the transmission and thermopower curves were analyzed. CdSe-diamantane (Cd7Se7) and CdSe-tetramantane (Cd11Se11) junctions exhibited the best thermoelectric performance due to their low surface reconstruction energy, which is attributed to the number of dangling and unsaturated bonds. This study guides the design of new molecular junctions with desired thermoelectric properties. The electrical and thermal properties of cadmium selenide (CdnSen) molecular junctions (n = 7, 11, 13) were investigated using a ballistic quantum transport method based on the non-equilibrium Green's function (NEGF) approach. Thermoelectric properties were calculated for the molecular junctions with different structures before and after hydrogen passivation. Density functional theory (DFT) calculations were performed at the B3LYP level with the 3-21G basis set for the Cd atoms and the 6-31G** basis set for the Se atoms. The SIESTA and GOLLUM codes were used to study the effect of changing the shape and size of each structure on its electrical and thermal characteristics.

Kinetics effect of hydrogen passivation on the zigzag edge growth of h-BN

Edge kinetics in 2D structures has been a key to understanding the growth. In this paper, the effect of hydrogen passivation on the growth of hexagonal boron nitride (h-BN) was studied. Without hydrogen, the filling process of the gap on bare edges of h-BN is difficult because of the formation of dimers that distorts the edge. With hydrogen passivation, such difficulty can be largely reduced. In addition, hydrogen passivation can reduce the edge bending to the substrate. In summary, the amount of hydrogen passivation during the growth is the long-ignored parameter and can be the key to a good crystal quality.

Nanointerconnect design based on edge fluorinated/hydrogenated zigzag borophene nanoribbons: an ab initio analysis.

Using an ab initio framework and non-equilibrium Green's function technique, the effect of hydrogen and fluorine atom passivation on the electronic and transport properties of borophene nanoribbons (BNRs) are explored. For zigzag edge states, we have explored all potentially stable combinations of hydrogen and fluorine passivation. Fluorine passivation leads to thermodynamically stable structures with improved stability for the increased concentration of F atoms, according to our binding energy (Eb) calculations. Furthermore, density-of-states and dispersion relation (E-k structures) computations indicate that fluorine-passivated BNRs are primarily metallic in nature. We proposed these nanostructures for their use in metal interconnects because of their increased metallicity. We have used the typical two-probe setup to calculate the critical parameters like quantum resistance (RQ), kinetic inductance (LK), and quantum capacitance (CQ) to evaluate their performance as metal interconnects. Because they have the lowest estimated values of LK = 26.1 nH μm-1, and CQ = 399 pF cm-1, the zigzag BNRs (ZBNRs) with two edge fluorinated (F-BNR-F) nanostructures may be considered as a promising candidate for nanoscale interconnect applications.

InGaN-based green micro-LED efficiency enhancement by hydrogen passivation of the p-GaN sidewall

We investigated the effect of the sidewall passivation by hydrogen plasma on the InGaN green micro-LED performance. Hydrogen passivation deactivates the surface region of p-GaN around the perimeter of the device mesa. Thus, hole injection is suppressed in this region, where etching-caused material degradation results in leakage current, decreasing device efficiency. We have confirmed the hydrogen passivation effect on LED square pixels with sizes of 20 and 100 μm. For smaller LEDs, the reverse leakage current has reduced more than tenfold, and the external quantum efficiency of LEDs was enhanced 1.4-times due to the suppression of the non-radiative recombination.

Optical and Mechanical Properties of Europium-Doped Silicon Oxynitride Thin Films

Light emission from silicon-based systems has gained significant interest over the past few decades with the vision of developing an optoelectronic platform that can be integrated with the existing metal-oxide-semiconductor (MOS) technology [1]. Rare earth doping of silicon-based materials is a promising approach to fabricating efficient light emitting devices because of their excellent luminescence properties and their chemical stability [2]. Europium (Eu) ions are attractive dopants for silicon photonic applications due to their intense emission in the visible spectral region. The efficiency of such photonic devices can be influenced by the mechanical properties of the Eu-doped films. Thus, the integration of these films in photonic devices requires an understanding of their mechanical properties as well. In this work, we discuss the relationship between the photoluminescence (PL) behavior and the elasticity and hardness of Eu doped silicon oxynitride (SiON) thin films.We have fabricated thin films using an electron cyclotron resonance plasma-enhanced chemical vapor deposition system with integrated magnetron sputtering system [3] on p-type 3” Si (100) substrates. Silane (diluted in 90% argon) and nitrogen (diluted in 90% argon) were used as precursor gases, while a 99.9% pure Eu sputtering target was used as a sputtering source. Different sets of samples were fabricated by changing the sputtering power and argon flow rate to understand the effect of deposition parameters on the dopant concentration and the optical and mechanical properties. Post-deposition annealing in nitrogen and a mixture of nitrogen with hydrogen (5%) were performed over a wide range of temperatures from 600° to 1100° C. The effect of hydrogen passivation was studied as well. The atomic concentration of the constituents was identified by Rutherford backscattering spectrometry. Optical properties were investigated by variable angle spectroscopic ellipsometry (VASE) analysis. The PL spectra were obtained at room temperature with a laser diode excitation source, operating at a wavelength of 375nm. Finally, we performed nanoindentation measurements to understand the deformation behavior of SiON films with the incorporation of Eu. The indentation hardness and Young’s modulus of the films were investigated, respectively, for different Eu concentrations and different deposition parameters.Reference[1] A. Moadhen, H. Elhouichet, M. Oueslati, and M. Férid, “Photoluminescence properties of europium-doped porous silicon nanocomposites,” J. Lumin., vol. 99, no. 1, pp. 13–17, 2002, doi: 10.1016/S0022-2313(02)00322-8.[2] Z. Lin R. Huang, H. Wang, Y. Wang, Y. Zhang, Y. Gao, J. Song, C. Song, H. Li, “Dense nanosized europium silicate clusters induced light emission enhancement in Eu-doped silicon oxycarbide films,” J. Alloys Compd., vol. 694, pp. 946–951, 2017, doi: 10.1016/j.jallcom.2016.10.132.[3] J. W. Miller, Z. Khatami, J. Wojcik, J. D. B. Bradley, and P. Mascher, “Integrated ECR-PECVD and magnetron sputtering system for rare-earth-doped Si-based materials,” Surf. Coatings Technol., vol. 336, pp. 99–105, 2018, doi: 10.1016/j.surfcoat.2017.08.051.

Large suppression of spin-relaxation rate in graphene nanoribbons in the presence of magnetic impurities

Achievement of low spin-relaxation rate is an important goal for spintronics development. We study the spin-relaxation rate arising from a low concentration of magnetic impurities in armchair graphene nanoribbons (AGNR). Large suppression in the spin-relaxation rate, exhibited as dip structures, is found when the Fermi energy approaches a subband band edge. This suppression originated from the quasi-one-dimensional density of states and is manifested via the singular features in the AGNR same-site Green's function ${G}_{\mathcal{II}}$, where $\mathcal{I}$ denotes site locations of magnetic impurities. Analytic analysis of the spin-relaxation rate in the close vicinity of a subband band edge is performed to further reveal the physical nature of the suppression. The robustness of the suppression feature in the spin-relaxation rate is demonstrated by systematically increasing the number of magnetic impurities involved in a coherent multiple scattering with the electrons. Major peaks in the spin-relaxation rate are analyzed in light of their connection with spin-flipped resonances. Competition between magnetic impurities with similar resonance energies is found to lead to suppression in the spin-relaxation rate. Our calculations have taken into account the hydrogen-passivation effects at the AGNR edges when the hopping constant between edge carbons is modified.

Chemisorption Competition between H2O and H2 for Sites on the Si Surface under Xe+ Ion Bombardment: An XPS Study.

This paper reports the competition of H2O (residual) and H2 by site (defects) on the Si surface, created by Xe+ ion bombardment. X-ray photoelectron spectroscopy (XPS) in an ultrahigh vacuum system attached to the sample preparation chamber provided the data for the analyses. As hydrogen cannot be detected by XPS, an indirect method to evaluate the O and H cover ratio was developed. The hydrogen passivation effect obtained by the formation of the Si-H bond due to H2 chemisorption limits Si-OH and Si-O-Si bonds, which are products of H2O dissociation. In addition, the results have shown that Xe+ ion bombardment diminished the H2 chemisorption energy barrier onto Si.

Hybrid density functional theory study on zinc blende GaN and diamond surfaces and interfaces: Effects of size, hydrogen passivation, and dipole corrections

GaN-diamond heterojunctions show promise in high electron mobility transistor applications. This prompts the need for accurate models of structural and electronic properties. We detail here a hybrid density functional theory study of zinc blende (ZB) GaN and diamond heterostructures using slab supercell models. The dependence of electronic properties on supercell size, pseudo-hydrogen passivation, and dipole corrections is detailed. The larger bulk modulus of diamond is shown to provide a templating structure for GaN to grow upon, where the large lattice mismatch is accounted for through the inclusion of a cationic Ga adlayer. Looking at both type I and II surfaces and interfaces of GaN shows the instability of zb GaN without an adlayer (type II), where increased size, pseudo-hydrogen passivation and dipole corrections do not remove the spurious interaction between the top and bottom layers in type II GaN. Layer dependent density of states, local potential differences, and charge density differences show that the type I interface (with a Ga adlayer) is stable with an adhesion energy of 0.704 eV/Å2 (4.346 J/m2); interestingly, the diamond charge density intercalates into the first layer of GaN, which was seen experimentally for wurtzite GaN grown over diamond. The type II interface is shown to be unstable which implies that, to form a stable, thin-film zb interface between GaN and diamond, the partial pressure of trimethylgallium must be controlled to ensure a Ga layer exists both on the top and bottom layer of the GaN thin film atop the diamond. We believe our results lead to a better understanding of the GaN/diamond multifaceted interface present in the GaN overgrowth on diamond heterojunction used in electronic device applications.

Improved Resistive Switching Observed in Ti/Zr3N2/p-Si Capacitor via Hydrogen Passivation

Charge-trap based resistive switching (RS) has attracted attention in the resistive random-access memory (RRAM) industry due to its gradual RS behavior for multi-level and synaptic applications. In this work, in order to lower the operating current level closely related to device&#x2019;s degradation, we applied a hydrogen passivation to Zr₃N₂ based RRAM devices and investigated the correlation between current level and trap density, such as an interface trap density (<inline-formula> <tex-math notation="LaTeX">$\text{N}_{\mathrm {it}}$ </tex-math></inline-formula>) at the Zr<inline-formula> <tex-math notation="LaTeX">$_{3}\text{N}_{2}/p$ </tex-math></inline-formula>-Si layer and nitride trap density (<inline-formula> <tex-math notation="LaTeX">$\text{N}_{\mathrm {nt}}$ </tex-math></inline-formula>) within Zr₃N₂ films, for memory cells annealed in conventional N₂ gas as well as H₂ gas. Compared to the N₂-annealed sample, after H₂ annealing, <inline-formula> <tex-math notation="LaTeX">$\text{N}_{\mathrm {it}}$ </tex-math></inline-formula> is lowered by the hydrogen passivation effect, which results in a reduction of both current level at high resistive state (HRS) and variation of HRS and low resistive state (LRS). As a result, in the H₂ annealed Zr₃N₂ RRAM cell, we observed a lower operation voltage/current, longer endurance, and larger read margin due to the hydrogen passivation effect.

Silicon Wafer Gettering Design for Advanced CMOS Image Sensors Using Hydrocarbon Molecular Ion Implantation: A Review

We have developed silicon epitaxial wafers with high gettering capability using hydrocarbon molecular ion implantation for advanced Complementary Metal-Oxide-Semiconductor (CMOS) image sensors. These wafers have three unique silicon wafer characteristics for improvement of CMOS device electrical parameter such as high metallic impurity gettering, oxygen out-diffusion barrier effects from Czochralski silicon (CZ) substrate and hydrogen passivation effect for interface state defect at Si/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . We demonstrate that double epitaxial growth silicon wafers have an extremely high gettering capability during CMOS device fabrication process. We also found that gettering capability strongly dependence on oxygen impurity amount in hydrocarbon molecular ion implantation projection range. We believe that this novel silicon wafer can drastically contribute to the improvement of CMOS image sensor device performance such as white spot defect and dark current.

Registry-Dependent Potential for Interfaces of Gold with Graphitic Systems.

We present a semi-anisotropic interfacial potential (SAIP) designed to classically describe the interaction between gold and two-dimensional (2D) carbon allotropes such as graphene, fullerenes, or hydrocarbon molecules. The potential is able to accurately reproduce dispersion-corrected density functional theory (DFT+D3) calculations performed over selected configurations: a flat graphene sheet, a benzene molecule, and a C60 fullerene, physisorbed on the Au(111) surface. The effects of bending and hydrogen passivation on the potential terms are discussed. The presented SAIP provides a noticeable improvement in the state-of-the-art description of Au–C interfaces. Furthermore, its functional form is suitable to describe the interfacial interaction between other 2D and bulk materials.

Photoluminescence and Crystal Structure of Eu Doped Silicon Oxide Prepared By Hybrid Sputtering and ECR-PECVD

Silicon based light emitters have attracted a considerable interest due to its potential application in emerging technology in the field of solid-state lightening (SSL), solar cells, light emitting diodes (LEDs) and displays. Sharp and well-defined, 4f transition emission of rare earth (RE) elements drive RE doping to be one of the major approaches for enhancing the optical properties of silicon-based materials and it has drawn a significant attention over the last few decades [1]. Cerium (Ce) and terbium (Tb) correspond to blue and green light emission, respectively, and they have been developed to some extent. However, achieving the red-light emission which attributes to the trivalent europium (Eu) oxidation state is more challenging due to the change between the two oxidation states of Eu (Eu2+ and Eu3+) [2].In this work, a set of Eu doped oxygen rich silicon oxide (ORSO) thin films are fabricated using an integrated magnetron sputtering and electron cyclotron resonance plasma enhanced chemical vapor deposition (IMS-ECR-PECVD) system [3]. Following the deposition, the thin films are subjected to annealing using pure nitrogen (N2) and 95% of nitrogen and 5% of hydrogen (N2+H2) atmospheres and different temperatures ranging from 300 to 1350 °C. Performing the photoluminescence (PL) measurements shows that thin films annealed at elevated temperatures (above 1000 °C) exhibit more intense luminescence compared to the ones annealed at lower temperatures (below 900 °C). At annealing temperatures as low as 300 °C, PL intensity at 615 nm which is corresponding to 5D0 to 7F2 transition of trivalent Eu ion is observed. Furthermore, the effect of hydrogen passivation is investigated (as shown in Figure. 1.a) confirming the passivation resulting in an increase of PL intensity by one order of magnitude.Performing Rutherford backscattering spectroscopy (RBS) it is verified the Eu concentration of the thin films vary from 0.17 at. % to 6.36 at. %. It is observed that through IMS-ERC-PECVD system, the concentration of the RE, in this case Eu, can be controlled by manipulating the deposition parameters while the sputtering power shows the most considerable influence. Variable angle spectroscopy ellipsometry (VASE) is conducted to obtain the refractive index and thickness of the thin films. The incorporation of more hydrogen decreases the refractive index whereas the thickness is inversely proportional to hydrogen increase in the deposited film.X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM) explain the PL behavior for samples annealed at higher temperatures. The formation of EuxSiyOz crystals approves the intense PL emission of samples annealed at elevated temperatures (above 1000 ºC) particularly at 1350 ºC while for the samples annealed at temperatures below 800 °C, the structure remains amorphous (shown in Figure 1.b).

Effect of Sputtering Parameters on the Optical Properties of Luminescent Eu-Doped SiOx Thin Films

Luminescent silicon (Si) based structures that are compatible with the existing complementary metal oxide semiconductor industry has drawn significant interest with the vision of developing an integrated optoelectronic platform on monolithic Si [1]. Such luminescent structures find several applications in inter- and intra-chip optical interconnects, microdisplay, biological detections, and solid-state lighting [2, 3]. The outstanding optical properties and chemical stability of rare earth materials make doping Si with rare earths a promising approach to obtain bright emission from Si-based structures [4].In this work, we have investigated the influence of sputtering power and argon (Ar) partial pressure on the optical properties and the composition of europium (Eu) doped silicon oxide (SiOx) thin films. For this purpose, the thin films were fabricated by electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD) with in-situ magnetron sputtering on a p-type 3" Si (100) substrate. Silane (SiH4) and oxygen (O2) were used as precursor gases, and a solid 99.9% pure Eu as the sputtering target. Ar was used as the sputtering gas and brought into the chamber through a gas injection ring. A set of samples was prepared by changing the Ar flow rate ranging from 10 to 40 cubic centimeters per minute at standard temperature and pressure (sccm) in steps of 10 sccm. Another set of samples was fabricated by varying the sputtering power from 20 to 30W in steps of 5W. Post-deposition annealing was performed at a higher temperature from 900°C to 1200°C in ambient nitrogen and a mixture of nitrogen (95%) and hydrogen (5%) atmosphere. The effect of hydrogen passivation has also been studied in this work. The compositional analysis was performed by Rutherford backscattering spectrometry (RBS) and elastic recoil detection analysis (ERDA). We found that the doping concentration was strongly influenced by the sputtering power, and it is slightly affected by the Ar partial pressure. The thickness, refractive index, and absorption coefficient of the thin films were obtained from variable angle spectroscopic ellipsometry (VASE) analysis. The dependency of the thickness and the optical parameters on sputtering power and Ar partial pressure was also analyzed. In addition, the luminescence properties of Eu doped SiOx films have been investigated. A bright white emission was observed due to the transition between 4f65d and 4f7energy levels of Eu2+ ion from all the films, which can be seen by the naked eye under daylight conditions. The relation between intensity and doping concentration was also discussed.[1] Lin, R. Huang, H. Wang, Y. Wang, Y. Zhang, Y. Guo, ... and H. Li, “Dense nanosized europium silicate clusters induced light emission enhancement in Eu-doped silicon oxycarbide films,” J. Alloys Compd., vol. 694, pp. 946–951, 2017, doi: 10.1016/j.jallcom.2016.10.132.[2] D. Thomson, A. Zilkie, J. E. Bowers, T. Komljenovic, G. T. Reed, L. Vivien, ... and J. M. Hartmann, , “Roadmap on silicon photonics,” J. Opt. (United Kingdom), vol. 18, no. 7, pp. 1–20, 2016, doi: 10.1088/2040-8978/18/7/073003.[3] H. Jeong, S. Lee, G. Y. Sung, and J. H. Shin, “Design and fabrication of Tb3+-doped silicon oxy-nitride microdisk for biosensor applications,” IEEE Photonics Technol. Lett., vol. 23, no. 2, pp. 88–90, 2011, doi: 10.1109/LPT.2010.2091268.[4] L. Li, J. Zheng, Y. Zuo, B. Cheng, and Q. Wang, “Strong Eu2+ light emission in Eu silicate through Eu3+ reduction in Eu2O3/Si multilayer deposited on Si substrates,” Nanoscale Res. Lett., vol. 8, no. 1, p. 194, 2013, doi: 10.1186/1556-276x-8-194.

Conductance and dielectric properties of hydrogen and hydroxyl passivated SiCNWs* *Project supported by the National Natural Science Foundation of China (Grant No. 11574261) and the Natural Science Foundation of Hebei Province, China (Grant No. A2021203030).

Based on the transport theory and the polarization relaxation model, the effects of hydrogen and hydroxyl passivation on the conductivity and dielectric properties of silicon carbide nanowires (SiCNWs) with different sizes are numerically simulated. The results show that the variation trend of conductivity and band gap of passivated SiCNWs are opposite to the scenario of the size effect of bare SiCNWs. Among the influencing factors of conductivity, the carrier concentration plays a leading role. In the dielectric properties, the bare SiCNWs have a strong dielectric response in the blue light region, while passivated SiCNWs show a more obvious dielectric response in the far ultraviolet-light region. In particular, hydroxyl passivation produces a strong dielectric relaxation in the microwave band, indicating that hydroxyl passivated SiCNWs have a wide range of applications in electromagnetic absorption and shielding.

Effects of Hydrogen Passivation on Fullerene-Derived Si30C30 Clusters

Silicon carbide (SiC) is technologically a significant material. A recent report on the abundance of C60 fullerenes in interstellar space, along with the presence of the SiC precursors, sparked interest in potentially similar SiC nanostructures. The C60 fullerene was found experimentally and is an exceptionally stable form of carbon. As Si and C have similar valence electron properties, it has been long envisioned that Si and SiC could also form similar fullerene type structures. In this paper, Si30C30 fullerene-derived clusters were studied from the first principle starting from an ideal Si60 fullerene templet with various arrangements of silicon and carbon atoms, and then relax them without any symmetry constraint. Hydrogen passivation was considered as well to model the effect of ligands that may be available during the chemical synthesis processes. We have found that after passivation, the relative stability of different configurations of Si30C30 clusters changed compared to the unpassivated structures, while some structures collapsed. We have also noticed several Si-Si and Si-C double bonds in the unpassivated structures. Upon relaxation, some Si atoms lost their hydrogen, while carbon atoms capture those hydrogen atoms. Finally, we tested the endohedral doping of a transition metal, tungsten atom, to stabilize and magnetize Si30C30. With hydrogen passivation, the magnetic moment on W atom was enhanced. Overall, the effects of passivation on these fullerene structures are not very straightforward.

First-principles Study of the Impact of Hydrogen Passivation on the Charge State Transition Levels of the CiOi(Sii)n Defect Complexes in Silicon

Density functional theory (DFT) with the Heyd-Scuseria-Ernzerhof hybrid functional has been used to predict the stability, formation energy, geometric structure, and the charge state transition levels of the CiOi(Sii)n (i = interstitial) defect complex in silicon for n = 0, 1, 2. The effect of hydrogen passivation on the properties of the CiOi(Sii)n defect complex is also investigated. The results for the binding energies confirm the stability of the defect complexes at neutral charge state. The charge state transition levels show that CiOi induces a shallow donor level and a deep acceptor level. The CiOiSii and CiOi(Sii)2 however induced deep donor levels. After hydrogen passivation, the acceptor level of the CiOiSii and the CiOi(Sii)i defect complexes disappear and the donor levels for all the defect complexes move deeper in the band gap.

Effect of Isovalent Doping on Hydrogen Passivated Vacancy-oxygen Defect Complexes in Silicon: Insights from Density Functional Theory

Using the hybrid density functional theory (DFT) computational approach, we examine the effect of hydrogen passivation and isovalent doping on the vacancy(Vn)-oxygen interstitial(Oi), i.e., Vn-Omi (n, m = 0,1,2) defect complexes in silicon. Specifically, we study the structural properties, relative stability and defect levels induced by the V, V2, VOi, V2Oi VO2i defect complexes. We found that hydrogen passivation improve the electrical activity of silicon vacancy and divacancy, but has negative or undesirable effect on the electrical activity of VOi, V2Oi VO2i defect complexes. To remove the negative effect of hydrogen passivation, isovalent doping of VOi, V2Oi VO2i defect complexes with each of Ge, Sn and Pb is carried out. This is found to improve the electrical activity of the defect complexes by shifting the defect-induced acceptor and shallow donor levels deep into the valence and the conduction bands, respectively. Our work emphasizes the importance of isovalent doping in improving the electrical activity of silicon containing hydrogen and vacancy-oxygen defect complexes.